Submitted:
08 May 2026
Posted:
11 May 2026
You are already at the latest version
Abstract
Keywords:
1. Introduction
Research Questions and Aims
2. Methodological and Conceptual Framework
2.1. Methodological Approach
2.2. Conceptual Contribution and Positioning
3. Closing the Monitoring-Decision Gap: Interpreting Data for Action
3.1. The Practical Meaning of Internal-External Load Mismatch
4. Monitoring Domains for Adaptive Training
5. The LOAD-R Framework
5.1. Load
5.2. Organism Response
5.3. Adaptive State
5.4. Decision
5.5. Re-Evaluation
6. Decision Zones and Training Actions
7. Athlete Response Archetypes and Individualization
8. Field Implementation Across Resource Levels

8.1. Applied Microcycle Example: Operationalizing LOAD-R in Practice
9. Testable Predictions Emerging from the Framework
10. Methodological Limitations and Future Directions
11. Discussion
Practical Applications
12. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
Abbreviations
| ACWR | acute:chronic workload ratio |
| AMS | athlete management system |
| CMJ | countermovement jump |
| GPS | global positioning system |
| HR | heart rate |
| HRV | heart rate variability |
| LOAD-R | Load, Organism response, Adaptive state, Decision, Re-evaluation |
| RPE | rating of perceived exertion |
| RSI | reactive strength index |
| SEM | standard error of measurement |
| sRPE | session rating of perceived exertion |
| TRIMP | training impulse |
References
- Bourdon, P.C.; Cardinale, M.; Murray, A.; Gastin, P.; Kellmann, M.; Varley, M.C.; Gabbett, T.J.; Coutts, A.J.; Burgess, D.J.; Gregson, W.; Cable, N.T. Monitoring athlete training loads: consensus statement. Int. J. Sports Physiol. Perform. 2017, 12, S2-161-S2-170. [Google Scholar] [CrossRef] [PubMed]
- Rago, V.; Brito, J.; Figueiredo, P.; Costa, J.; Krustrup, P.; Rebelo, A. Relationship between external load and perceptual responses to training in professional football: effects of quantification method. Sports 2019, 7, 68. [Google Scholar] [CrossRef]
- Bellinger, P.M. Functional overreaching in endurance athletes: a necessity or cause for concern? Sports Med. 2020, 50, 1059–1073. [Google Scholar] [CrossRef] [PubMed]
- Gabbett, T.J.; Nassis, G.P.; Oetter, E.; Pretorius, J.; Johnston, N.; Medina, D.; Rodas, G.; Myslinski, T.; Howells, D.; Beard, A.; Ryan, A. The athlete monitoring cycle: a practical guide to interpreting and applying training monitoring data. Br. J. Sports Med. 2017, 51, 1451–1452. [Google Scholar] [CrossRef]
- Halson, S.L. Monitoring training load to understand fatigue in athletes. Sports Med. 2014, 44, S139–S147. [Google Scholar] [CrossRef] [PubMed]
- Impellizzeri, F.M.; Shrier, I.; McLaren, S.J.; Coutts, A.J.; McCall, A.; Slattery, K.; Jeffries, A.C.; Kalkhoven, J.T. Understanding training load as exposure and dose. Sports Med. 2023, 53, 1667–1679. [Google Scholar] [CrossRef]
- Akenhead, R.; Nassis, G.P. Training load and player monitoring in high-level football: current practice and perceptions. Int. J. Sports Physiol. Perform. 2016, 11, 587–593. [Google Scholar] [CrossRef]
- Saw, A.E.; Main, L.C.; Gastin, P.B. Monitoring the athlete training response: subjective self-reported measures trump commonly used objective measures. Br. J. Sports Med. 2016, 50, 281–291. [Google Scholar] [CrossRef]
- Alba-Jimenez, C.; Moreno-Doutres, D.; Pena, J. Trends assessing neuromuscular fatigue in team sports: a narrative review. Sports 2022, 10, 33. [Google Scholar] [CrossRef]
- McGuigan, M.R. Monitoring Training and Performance in Athletes; Human Kinetics: Champaign, IL, USA, 2017. [Google Scholar] [CrossRef]
- Robertson, S.; Bartlett, J.D.; Gastin, P.B. Red, amber, or green? Athlete monitoring in team sport: the need for decision-support systems. Int. J. Sports Physiol. Perform. 2017, 12, S2-73-S2-79. [Google Scholar] [CrossRef]
- Bartlett, J.D.; O’Connor, F.; Pitchford, N.; Torres-Ronda, L.; Robertson, S.J. Relationships between internal and external training load in team-sport athletes: evidence for an individualized approach. Int. J. Sports Physiol. Perform. 2017, 12, 230–234. [Google Scholar] [CrossRef]
- McLaren, S.J.; Macpherson, T.W.; Coutts, A.J.; Hurst, C.; Spears, I.R.; Weston, M. The relationships between internal and external measures of training load and intensity in team sports: a meta-analysis. Sports Med. 2018, 48, 641–658. [Google Scholar] [CrossRef]
- Vanrenterghem, J.; Nedergaard, N.J.; Robinson, M.A.; Drust, B. Training load monitoring in team sports: a novel framework separating physiological and biomechanical load-adaptation pathways. Sports Med. 2017, 47, 2135–2142. [Google Scholar] [CrossRef] [PubMed]
- Baethge, C.; Goldbeck-Wood, S.; Mertens, S. SANRA-a scale for the quality assessment of narrative review articles. Res. Integr. Peer Rev. 2019, 4, 5. [Google Scholar] [CrossRef] [PubMed]
- Imbach, F.; Sutton-Charani, N.; Montmain, J.; Candau, R.; Perrey, S. The use of fitness-fatigue models for sport performance modelling: conceptual issues and contributions from machine-learning. Sports Med. Open 2022, 8, 29. [Google Scholar] [CrossRef] [PubMed]
- Turner, J.D.; Mazzoleni, M.J.; Little, J.A.; Sequeira, D.; Mann, B.P. A nonlinear model for the characterization and optimization of athletic training and performance. Biomed. Hum. Kinet. 2017, 9, 82–93. [Google Scholar] [CrossRef]
- Imbach, F.; Perrey, S.; Chailan, R.; Meline, T.; Candau, R. Training load responses modelling and model generalisation in elite sports. Sci. Rep. 2022, 12, 1586. [Google Scholar] [CrossRef]
- Mujika, I.; Halson, S.; Burke, L.M.; Balague, G.; Farrow, D. An integrated, multifactorial approach to periodization for optimal performance in individual and team sports. Int. J. Sports Physiol. Perform. 2018, 13, 538–561. [Google Scholar] [CrossRef]
- Kiely, J. Periodization paradigms in the 21st century: evidence-led or tradition-driven? Int. J. Sports Physiol. Perform. 2012, 7, 242–250. [Google Scholar] [CrossRef]
- Mănescu, D.C. Training Load Oscillation and Epigenetic Plasticity: Molecular Pathways Connecting Energy Metabolism and Athletic Personality. Int. J. Mol. Sci. 2026, 27, 792. [Google Scholar] [CrossRef]
- Bompa, T.O.; Buzzichelli, C. Periodization: Theory and Methodology of Training, 6th ed.; Human Kinetics: Champaign, IL, USA, 2019. [Google Scholar] [CrossRef]
- Jones, C.M.; Griffiths, P.C.; Mellalieu, S.D. Training load and fatigue marker associations with injury and illness: a systematic review of longitudinal studies. Sports Med. 2017, 47, 943–974. [Google Scholar] [CrossRef]
- Soligard, T.; Schwellnus, M.; Alonso, J.M.; Bahr, R.; Clarsen, B.; Dijkstra, H.P.; Gabbett, T.; Gleeson, M.; Hagglund, M.; Hutchinson, M.R.; Janse van Rensburg, C.; Khan, K.M.; Meeusen, R.; Orchard, J.W.; Pluim, B.M.; Raftery, M.; Budgett, R.; Engebretsen, L. How much is too much? IOC consensus statement on load in sport and risk of injury. Br. J. Sports Med. 2016, 50, 1030–1041. [Google Scholar] [CrossRef] [PubMed]
- Gabbett, T.J. The training-injury prevention paradox: should athletes be training smarter and harder? Br. J. Sports Med. 2016, 50, 273–280. [Google Scholar] [CrossRef]
- Drew, M.K.; Finch, C.F. The relationship between training load and injury, illness and soreness: a systematic review. Sports Med. 2016, 46, 861–883. [Google Scholar] [CrossRef] [PubMed]
- Windt, J.; Gabbett, T.J. How do training and competition workloads relate to injury? The workload-injury aetiology model. Br. J. Sports Med. 2017, 51, 428–435. [Google Scholar] [CrossRef]
- Hulin, B.T.; Gabbett, T.J.; Lawson, D.W.; Caputi, P.; Sampson, J.A. The acute:chronic workload ratio predicts injury: high chronic workload may decrease injury risk in elite rugby league players. Br. J. Sports Med. 2016, 50, 231–236. [Google Scholar] [CrossRef] [PubMed]
- Blanch, P.; Gabbett, T.J. Has the athlete trained enough to return to play safely? The acute:chronic workload ratio permits clinicians to quantify a player’s risk of subsequent injury. Br. J. Sports Med. 2016, 50, 471–475. [Google Scholar] [CrossRef]
- Impellizzeri, F.M.; Tenan, M.S.; Kempton, T.; Novak, A.; Coutts, A.J. Acute:chronic workload ratio: conceptual issues and fundamental flaws. Int. J. Sports Physiol. Perform. 2020, 15, 907–913. [Google Scholar] [CrossRef]
- Wang, C.; Vargas, J.T.; Stokes, T.; Steele, R.; Shrier, I. Analyzing activity and injury: lessons learned from the acute:chronic workload ratio. Sports Med. 2020, 50, 1243–1254. [Google Scholar] [CrossRef]
- Menaspa, P. Are rolling averages a good way to assess training load for injury prevention? Br. J. Sports Med. 2017, 51, 618–619. [Google Scholar] [CrossRef]
- Carey, D.L.; Blanch, P.; Ong, K.L.; Crossley, K.M.; Crow, J.; Morris, M.E. Training loads and injury risk in Australian football-differing acute:chronic workload ratios influence match injury risk. Br. J. Sports Med. 2017, 51, 1215–1220. [Google Scholar] [CrossRef]
- Esmaeili, A.; Hopkins, W.G.; Stewart, A.M.; Elias, G.P.; Lazarus, B.H.; Aughey, R.J. The individual and combined effects of multiple factors on the risk of soft tissue non-contact injuries in elite team sport athletes. Front. Physiol. 2018, 9, 1280. [Google Scholar] [CrossRef]
- Williams, S.; West, S.; Cross, M.J.; Stokes, K.A. Better way to determine the acute:chronic workload ratio? Br. J. Sports Med. 2017, 51, 209–210. [Google Scholar] [CrossRef]
- Cummins, C.; Orr, R.; O’Connor, H.; West, C. Global positioning systems (GPS) and microtechnology sensors in team sports: a systematic review. Sports Med. 2013, 43, 1025–1042. [Google Scholar] [CrossRef]
- Malone, J.J.; Lovell, R.; Varley, M.C.; Coutts, A.J. Unpacking the black box: applications and considerations for using GPS devices in sport. Int. J. Sports Physiol. Perform. 2017, 12, S2-18-S2-26. [Google Scholar] [CrossRef] [PubMed]
- Buchheit, M.; Simpson, B.M. Player-tracking technology: half-full or half-empty glass? Int. J. Sports Physiol. Perform. 2017, 12, S2-35-S2-41. [Google Scholar] [CrossRef] [PubMed]
- Aughey, R.J. Applications of GPS technologies to field sports. Int. J. Sports Physiol. Perform. 2011, 6, 295–310. [Google Scholar] [CrossRef] [PubMed]
- Varley, M.C.; Fairweather, I.H.; Aughey, R.J. Validity and reliability of GPS for measuring instantaneous velocity during acceleration, deceleration, and constant motion. J. Sports Sci. 2012, 30, 121–127. [Google Scholar] [CrossRef] [PubMed]
- Johnston, R.J.; Watsford, M.L.; Kelly, S.J.; Pine, M.J.; Spurrs, R.W. Validity and interunit reliability of 10 Hz and 15 Hz GPS units for assessing athlete movement demands. J. Strength Cond. Res. 2014, 28, 1649–1655. [Google Scholar] [CrossRef]
- Jennings, D.; Cormack, S.; Coutts, A.J.; Boyd, L.; Aughey, R.J. Variability of GPS units for measuring distance in team sport movements. Int. J. Sports Physiol. Perform. 2010, 5, 565–569. [Google Scholar] [CrossRef]
- Boyd, L.J.; Ball, K.; Aughey, R.J. The reliability of MinimaxX accelerometers for measuring physical activity in Australian football. Int. J. Sports Physiol. Perform. 2011, 6, 311–321. [Google Scholar] [CrossRef]
- Nicolella, D.P.; Torres-Ronda, L.; Saylor, K.J.; Schelling, X. Validity and reliability of an accelerometer-based player tracking device. PLoS ONE 2018, 13, e0191823. [Google Scholar] [CrossRef] [PubMed]
- Scott, B.R.; Lockie, R.G.; Knight, T.J.; Clark, A.C.; de Jonge, X.A.K.J. A comparison of methods to quantify the in-season training load of professional soccer players. Int. J. Sports Physiol. Perform. 2013, 8, 195–202. [Google Scholar] [CrossRef]
- Brink, M.S.; Nederhof, E.; Visscher, C.; Schmikli, S.L.; Lemmink, K.A.P.M. Monitoring load, recovery, and performance in young elite soccer players. J. Strength Cond. Res. 2010, 24, 597–603. [Google Scholar] [CrossRef] [PubMed]
- Marynowicz, J.; Kikut, K.; Lango, M.; Horna, D.; Andrzejewski, M. Relationship between the session-RPE and external measures of training load in youth soccer training. J. Strength Cond. Res. 2020, 34, 2800–2804. [Google Scholar] [CrossRef] [PubMed]
- Askow, A.T.; Lobato, A.L.; Arndts, D.J.; Jennings, W.; Kreutzer, A.; Erickson, J.L.; Jagim, A.R.; Camic, C.L. Session rating of perceived exertion load and training impulse are strongly correlated to GPS-derived measures of external load in NCAA Division I women’s soccer athletes. J. Funct. Morphol. Kinesiol. 2021, 6, 90. [Google Scholar] [CrossRef]
- Tibana, R.A.; de Sousa, N.M.F.; Cunha, G.V.; Prestes, J.; Fett, C.; Gabbett, T.J.; Voltarelli, F.A. Validity of session rating perceived exertion method for quantifying internal training load during high-intensity functional training. Sports 2018, 6, 68. [Google Scholar] [CrossRef]
- Helms, E.R.; Cronin, J.; Storey, A.; Zourdos, M.C. Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength Cond. J. 2016, 38, 42–49. [Google Scholar] [CrossRef]
- Haddad, M.; Stylianides, G.; Djaoui, L.; Dellal, A.; Chamari, K. Session-RPE method for training load monitoring: validity, ecological usefulness, and influencing factors. Front. Neurosci. 2017, 11, 612. [Google Scholar] [CrossRef]
- Manzi, V.; D’Ottavio, S.; Impellizzeri, F.M.; Chaouachi, A.; Chamari, K.; Castagna, C. Profile of weekly training load in elite male professional basketball players. J. Strength Cond. Res. 2010, 24, 1399–1406. [Google Scholar] [CrossRef]
- Gallo, T.F.; Cormack, S.J.; Gabbett, T.J.; Lorenzen, C.H. Self-reported wellness profiles of professional Australian football players during the competition phase of the season. J. Strength Cond. Res. 2017, 31, 495–502. [Google Scholar] [CrossRef] [PubMed]
- Lambert, M.I.; Borresen, J. Measuring training load in sports. Int. J. Sports Physiol. Perform. 2010, 5, 406–411. [Google Scholar] [CrossRef] [PubMed]
- Meeusen, R.; Duclos, M.; Foster, C.; Fry, A.; Gleeson, M.; Nieman, D.; Raglin, J.; Rietjens, G.; Steinacker, J.; Urhausen, A. Prevention, diagnosis and treatment of the overtraining syndrome: joint consensus statement. Med. Sci. Sports Exerc. 2013, 45, 186–205. [Google Scholar] [CrossRef] [PubMed]
- Kellmann, M. Preventing overtraining in athletes in high-intensity sports and stress/recovery monitoring. Scand. J. Med. Sci. Sports 2010, 20, 95–102. [Google Scholar] [CrossRef]
- Kellmann, M.; Bertollo, M.; Bosquet, L.; Brink, M.; Coutts, A.J.; Duffield, R.; Erlacher, D.; Halson, S.L.; Hecksteden, A.; Heidari, J.; Kallus, K.W.; Meeusen, R.; Mujika, I.; Robazza, C.; Skorski, S.; Venter, R.; Beckmann, J. Recovery and performance in sport: consensus statement. Int. J. Sports Physiol. Perform. 2018, 13, 240–245. [Google Scholar] [CrossRef]
- Brauers, J.J.; den Hartigh, R.J.R.; Jakowski, S.; Kellmann, M.; Wylleman, P.; Lemmink, K.A.P.M.; Brink, M.S. Monitoring the recovery-stress states of athletes: psychometric properties of the acute recovery and stress scale and short recovery stress scale among Dutch and Flemish athletes. J. Sports Sci. 2024, 42, 189–199. [Google Scholar] [CrossRef]
- Kreher, J.B.; Schwartz, J.B. Overtraining syndrome: a practical guide. Sports Health 2012, 4, 128–138. [Google Scholar] [CrossRef]
- Cadegiani, F.A.; Kater, C.E. Hormonal aspects of overtraining syndrome: a systematic review. BMC Sports Sci. Med. Rehabil. 2017, 9, 14. [Google Scholar] [CrossRef]
- Nedelec, M.; McCall, A.; Carling, C.; Legall, F.; Berthoin, S.; Dupont, G. Recovery in soccer: part I-post-match fatigue and time course of recovery. Sports Med. 2012, 42, 997–1015. [Google Scholar] [CrossRef]
- Nedelec, M.; McCall, A.; Carling, C.; Legall, F.; Berthoin, S.; Dupont, G. Recovery in soccer: part II-recovery strategies. Sports Med. 2013, 43, 9–22. [Google Scholar] [CrossRef]
- Mănescu, D.C.; Tudor, A.; Mănescu, A.M.; Mărgărit, I.R.; Mănescu, C.O.; Prisăcaru, C.; Păun, L.; Tudor, V. Antioxidants and Exercise: A Redox-Informed Framework for Training Adaptation, Performance, and Recovery. Antioxidants 2026, 15, 456. [Google Scholar] [CrossRef]
- Li, S.; Kempe, M.; Brink, M.; Lemmink, K. Effectiveness of recovery strategies after training and competition in endurance athletes: an umbrella review. Sports Med. Open 2024, 10, 55. [Google Scholar] [CrossRef]
- Fullagar, H.H.K.; Skorski, S.; Duffield, R.; Hammes, D.; Coutts, A.J.; Meyer, T. Sleep and athletic performance: the effects of sleep loss, sleep extension, and sleep interventions. Sports Med. 2015, 45, 161–186. [Google Scholar] [CrossRef] [PubMed]
- Stoian, M.; Mănescu, D.C. Training–Fuel Coupling (TFC): A Molecular Sports Nutrition Framework for Energy Availability, Chrono-Nutrition, and Performance Optimization. Nutrients 2026, 18, 693. [Google Scholar] [CrossRef]
- Lastella, M.; Roach, G.D.; Halson, S.L.; Sargent, C. Sleep/wake behaviours of elite athletes from individual and team sports. Eur. J. Sport Sci. 2015, 15, 94–100. [Google Scholar] [CrossRef] [PubMed]
- Walsh, N.P.; Halson, S.L.; Sargent, C.; Roach, G.D.; Nedelec, M.; Gupta, L.; Leeder, J.; Fullagar, H.H.K.; Coutts, A.J.; Edwards, B.J.; Pullinger, S.A.; Robertson, C.M.; Burniston, J.G.; Lastella, M.; Le Meur, Y.; Hausswirth, C.; Bender, A.M.; Grandner, M.A.; Samuels, C.H. Sleep and the athlete: narrative review and 2021 expert consensus recommendations. Br. J. Sports Med. 2021, 55, 356–368. [Google Scholar] [CrossRef]
- Bird, S.P. Sleep, recovery, and athletic performance: a brief review and recommendations. Strength Cond. J. 2013, 35, 43–47. [Google Scholar] [CrossRef]
- Daanen, H.A.M.; Lamberts, R.P.; Kallen, V.L.; Jin, A.; Van Meeteren, N.L.U. A systematic review on heart-rate recovery to monitor changes in training status in athletes. Int. J. Sports Physiol. Perform. 2012, 7, 251–260. [Google Scholar] [CrossRef]
- Bellenger, C.R.; Fuller, J.T.; Thomson, R.L.; Davison, K.; Robertson, E.Y.; Buckley, J.D. Monitoring athletic training status through autonomic heart rate regulation: a systematic review and meta-analysis. Sports Med. 2016, 46, 1461–1486. [Google Scholar] [CrossRef]
- Stanley, J.; Peake, J.M.; Buchheit, M. Cardiac parasympathetic reactivation following exercise: implications for training prescription. Sports Med. 2013, 43, 1259–1277. [Google Scholar] [CrossRef]
- Buchheit, M. Monitoring training status with HR measures: do all roads lead to Rome? Front. Physiol. 2014, 5, 73. [Google Scholar] [CrossRef]
- Plews, D.J.; Laursen, P.B.; Stanley, J.; Kilding, A.E.; Buchheit, M. Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring. Sports Med. 2013, 43, 773–781. [Google Scholar] [CrossRef] [PubMed]
- Flatt, A.A.; Esco, M.R. Evaluating individual training adaptation with smartphone-derived heart rate variability in a collegiate female soccer team. J. Strength Cond. Res. 2016, 30, 378–385. [Google Scholar] [CrossRef] [PubMed]
- Javaloyes, A.; Sarabia, J.M.; Lamberts, R.P.; Plews, D.; Moya-Ramon, M. Training prescription guided by heart-rate variability in cycling. Int. J. Sports Physiol. Perform. 2019, 14, 23–32. [Google Scholar] [CrossRef] [PubMed]
- Vesterinen, V.; Nummela, A.; Heikura, I.; Laine, T.; Hynynen, E.; Botella, J.; Häkkinen, K. Individual endurance training prescription with heart rate variability. Med. Sci. Sports Exerc. 2016, 48, 1347–1354. [Google Scholar] [CrossRef]
- Warr, D.M.; Pablos, C.; Sanchez-Alarcos, J.V.; Torres, V.; Izquierdo, J.M.; Redondo, J.C. Reliability of measurements during countermovement jump assessments: analysis of performance across subphases. Cogent Soc. Sci. 2020, 6, 1843835. [Google Scholar] [CrossRef]
- Thorpe, R.T.; Atkinson, G.; Drust, B.; Gregson, W. Monitoring fatigue status in elite team-sport athletes: implications for practice. Int. J. Sports Physiol. Perform. 2017, 12, S2-27-S2-34. [Google Scholar] [CrossRef]
- Gathercole, R.J.; Sporer, B.C.; Stellingwerff, T.; Sleivert, G.G. Alternative countermovement-jump analysis to quantify acute neuromuscular fatigue. Int. J. Sports Physiol. Perform. 2015, 10, 84–92. [Google Scholar] [CrossRef]
- Gathercole, R.J.; Sporer, B.C.; Stellingwerff, T.; Sleivert, G.G. Comparison of the capacity of different jump and sprint field tests to detect neuromuscular fatigue. J. Strength Cond. Res. 2015, 29, 2522–2531. [Google Scholar] [CrossRef]
- Claudino, J.G.; Cronin, J.; Mezencio, B.; McMaster, D.T.; McGuigan, M.; Tricoli, V.; Amadio, A.C.; Serrao, J.C. The countermovement jump to monitor neuromuscular status: a meta-analysis. J. Sci. Med. Sport 2017, 20, 397–402. [Google Scholar] [CrossRef]
- McLean, B.D.; Coutts, A.J.; Kelly, V.; McGuigan, M.R.; Cormack, S.J. Neuromuscular, endocrine, and perceptual fatigue responses during different length between-match microcycles in professional rugby league players. Int. J. Sports Physiol. Perform. 2010, 5, 367–383. [Google Scholar] [CrossRef]
- Twist, C.; Highton, J. Monitoring fatigue and recovery in rugby league players. Int. J. Sports Physiol. Perform. 2013, 8, 467–474. [Google Scholar] [CrossRef]
- Twist, C.; Waldron, M.; Highton, J.; Burt, D.; Daniels, M. Neuromuscular, biochemical and perceptual post-match fatigue in professional rugby league forwards and backs. J. Sports Sci. 2012, 30, 359–367. [Google Scholar] [CrossRef]
- Watkins, C.M.; Barillas, S.R.; Wong, M.A.; Archer, D.C.; Dobbs, I.J.; Lockie, R.G.; Coburn, J.W.; Tran, T.T.; Brown, L.E. Determination of vertical jump as a measure of neuromuscular readiness and fatigue. J. Strength Cond. Res. 2017, 31, 3305–3310. [Google Scholar] [CrossRef]
- Bishop, C.; Turner, A.; Read, P. Effects of inter-limb asymmetries on physical and sports performance: a systematic review. J. Sports Sci. 2018, 36, 1135–1144. [Google Scholar] [CrossRef]
- Fort-Vanmeerhaeghe, A.; Gual, G.; Romero-Rodriguez, D.; Unnitha, V. Lower limb neuromuscular asymmetry in volleyball and basketball players. J. Hum. Kinet. 2016, 50, 135–143. [Google Scholar] [CrossRef] [PubMed]
- Atkinson, G.; Batterham, A.M. True and false interindividual differences in the physiological response to an intervention. Exp. Physiol. 2015, 100, 577–588. [Google Scholar] [CrossRef] [PubMed]
- Hecksteden, A.; Kraushaar, J.; Scharhag-Rosenberger, F.; Theisen, D.; Senn, S.; Meyer, T. Individual response to exercise training: a statistical perspective. J. Appl. Physiol. 2015, 118, 1450–1459. [Google Scholar] [CrossRef] [PubMed]
- Koo, T.K.; Li, M.Y. A guideline of selecting and reporting intraclass correlation coefficients for reliability research. J. Chiropr. Med. 2016, 15, 155–163. [Google Scholar] [CrossRef]
- Liljequist, D.; Elfving, B.; Skavberg Roaldsen, K. Intraclass correlation: a discussion and demonstration of basic features. PLoS ONE 2019, 14, e0219854. [Google Scholar] [CrossRef]
- Curran-Everett, D. Explorations in statistics: the analysis of ratios and normalized data. Adv. Physiol. Educ. 2013, 37, 213–219. [Google Scholar] [CrossRef] [PubMed]
- Swinton, P.A.; Hemingway, B.S.; Saunders, B.; Gualano, B.; Dolan, E. A statistical framework to interpret individual response to intervention: paving the way for personalised nutrition and exercise prescription. Front. Nutr. 2018, 5, 41. [Google Scholar] [CrossRef] [PubMed]
- Hecksteden, A.; Pitsch, W.; Rosenberger, F.; Meyer, T. Repeated testing for the assessment of individual response to exercise training. J. Appl. Physiol. 2018, 124, 1567–1579. [Google Scholar] [CrossRef] [PubMed]
- Mann, T.N.; Lamberts, R.P.; Lambert, M.I. Methods of prescribing relative exercise intensity: physiological and practical considerations. Sports Med. 2013, 43, 613–625. [Google Scholar] [CrossRef]
- Buchheit, M. The numbers will love you back in return-I promise. Int. J. Sports Physiol. Perform. 2016, 11, 551–554. [Google Scholar] [CrossRef]
- Cormie, P.; McGuigan, M.R.; Newton, R.U. Developing maximal neuromuscular power: part 2 - training considerations for improving maximal power production. Sports Med. 2011, 41, 125–146. [Google Scholar] [CrossRef]
- Cormie, P.; McGuigan, M.R.; Newton, R.U. Developing maximal neuromuscular power: part 1-biological basis of maximal power production. Sports Med. 2011, 41, 17–38. [Google Scholar] [CrossRef]
- Suchomel, T.J.; Nimphius, S.; Stone, M.H. The importance of muscular strength in athletic performance. Sports Med. 2016, 46, 1419–1449. [Google Scholar] [CrossRef]
- Suchomel, T.J.; Nimphius, S.; Bellon, C.R.; Stone, M.H. The importance of muscular strength: training considerations. Sports Med. 2018, 48, 765–785. [Google Scholar] [CrossRef]
- Mănescu, A.M.; Hangu, S.Ș.; Mănescu, D.C. Nutritional Supplements for Muscle Hypertrophy: Mechanisms and Morphology—Focused Evidence. Nutrients 2025, 17, 3603. [Google Scholar] [CrossRef]
- Schoenfeld, B.J.; Grgic, J.; Van Every, D.W.; Plotkin, D.L. Loading recommendations for muscle strength, hypertrophy, and local endurance: a re-examination of the repetition continuum. Sports 2021, 9, 32. [Google Scholar] [CrossRef]
- Weakley, J.J.S.; Mann, B.; Banyard, H.G.; McLaren, S.; Scott, T.; Garcia-Ramos, A. Velocity-based training: from theory to application. Strength Cond. J. 2021, 43, 31–49. [Google Scholar] [CrossRef]
- Banyard, H.G.; Nosaka, K.; Haff, G.G. Reliability and validity of the load-velocity relationship to predict the one-repetition maximum back squat. J. Strength Cond. Res. 2017, 31, 1897–1904. [Google Scholar] [CrossRef] [PubMed]
- Gonzalez-Badillo, J.J.; Sanchez-Medina, L. Movement velocity as a measure of loading intensity in resistance training. Int. J. Sports Med. 2010, 31, 347–352. [Google Scholar] [CrossRef]
- Sanchez-Medina, L.; Gonzalez-Badillo, J.J. Velocity loss as an indicator of neuromuscular fatigue during resistance training. Med. Sci. Sports Exerc. 2011, 43, 1725–1734. [Google Scholar] [CrossRef] [PubMed]
- Pareja-Blanco, F.; Rodriguez-Rosell, D.; Sanchez-Medina, L.; Gorostiaga, E.M.; Gonzalez-Badillo, J.J. Effect of movement velocity during resistance training on neuromuscular performance. Int. J. Sports Med. 2014, 35, 916–924. [Google Scholar] [CrossRef] [PubMed]
- Mann, J.B.; Ivey, P.A.; Sayers, S.P. Velocity-based training in football. Strength Cond. J. 2015, 37, 52–57. [Google Scholar] [CrossRef]
- Scott, B.R.; Duthie, G.M.; Thornton, H.R.; Dascombe, B.J. Training monitoring for resistance exercise: theory and applications. Sports Med. 2016, 46, 687–698. [Google Scholar] [CrossRef]
- Schmitt, L.; Regnard, J.; Desmarets, M.; Mauny, F.; Mourot, L.; Fouillot, J.P.; Coulmy, N.; Millet, G.P. Fatigue shifts and scatters heart rate variability in elite endurance athletes. PLoS ONE 2013, 8, e71588. [Google Scholar] [CrossRef]
- Buchheit, M.; Racinais, S.; Bilsborough, J.C.; Bourdon, P.C.; Voss, S.C.; Hocking, J.; Cordy, J.; Mendez-Villanueva, A.; Coutts, A.J. Monitoring fitness, fatigue and running performance during a pre-season training camp in elite football players. J. Sci. Med. Sport 2013, 16, 550–555. [Google Scholar] [CrossRef]
- Brink, M.S.; Visscher, C.; Coutts, A.J.; Lemmink, K.A.P.M. Changes in perceived stress and recovery in overreached young elite soccer players. Scand. J. Med. Sci. Sports 2012, 22, 285–292. [Google Scholar] [CrossRef] [PubMed]
- Grandou, C.; Wallace, L.; Impellizzeri, F.M.; Allen, N.G.; Coutts, A.J. Overtraining in resistance exercise: an exploratory systematic review and methodological appraisal of the literature. Sports Med. 2020, 50, 815–828. [Google Scholar] [CrossRef] [PubMed]
- Mănescu, D.C.; Voinea, A.; Plastoi, C.D.; Iacobini, A.R.; Vulpe, A.A.; Pîrvan, A.; Dinciu, C.C.; Vulpe, B.I.; Băltărețu, C.; Iacobini, A. Molecular Biomarkers of Training Responses: A Systems Framework for Exercise Adaptation and Athlete Monitoring. Int. J. Mol. Sci. 2026, 27, 3601. [Google Scholar] [CrossRef] [PubMed]
- Le Meur, Y.; Pichon, A.; Schaal, K.; Schmitt, L.; Louis, J.; Gueneron, J.; Vidal, P.P.; Hausswirth, C. Evidence of parasympathetic hyperactivity in functionally overreached athletes. Med. Sci. Sports Exerc. 2013, 45, 2061–2071. [Google Scholar] [CrossRef]
- Mănescu, D.C.; Plăstoi, C.D.; Petre, R.L.; Mărgărit, I.R.; Mănescu, A.M.; Pîrvan, A. Metabolic Overdrive in Elite Sport: A Systems Model of AMPK–mTOR Oscillation, NAD+ Economy, and Epigenetic Drift. Int. J. Mol. Sci. 2026, 27, 1817. [Google Scholar] [CrossRef]
- Bellinger, P.; Desbrow, B.; Derave, W.; Lievens, E.; Irwin, C.; Sabapathy, S.; Kennedy, B.; Craven, J.; Pennell, E.; Rice, H.; Minahan, C. Muscle fiber typology is associated with the incidence of overreaching in response to overload training. J. Appl. Physiol. 2020, 129, 823–836. [Google Scholar] [CrossRef]
- Taylor, J.L.; Amann, M.; Duchateau, J.; Meeusen, R.; Rice, C.L. Neural contributions to muscle fatigue: from the brain to the muscle and back again. Med. Sci. Sports Exerc. 2016, 48, 2294–2306. [Google Scholar] [CrossRef]
- Pageaux, B. Perception of effort in exercise science: definition, measurement and perspectives. Eur. J. Sport Sci. 2016, 16, 885–894. [Google Scholar] [CrossRef]
- Noakes, T.D. Fatigue is a brain-derived emotion that regulates the exercise behavior to ensure the protection of whole body homeostasis. Front. Physiol. 2012, 3, 82. [Google Scholar] [CrossRef]
- Enoka, R.M.; Duchateau, J. Translating fatigue to human performance. Med. Sci. Sports Exerc. 2016, 48, 2228–2238. [Google Scholar] [CrossRef]
- Seiler, S. What is best practice for training intensity and duration distribution in endurance athletes? Int. J. Sports Physiol. Perform. 2010, 5, 276–291. [Google Scholar] [CrossRef]
- Stoggl, T.L.; Sperlich, B. Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training. Front. Physiol. 2014, 5, 33. [Google Scholar] [CrossRef]
- Rosenblat, M.A.; Perrotta, A.S.; Vicenzino, B. Polarized vs. threshold training intensity distribution on endurance sport performance: a systematic review and meta-analysis of randomized controlled trials. J. Strength Cond. Res. 2019, 33, 3491–3500. [Google Scholar] [CrossRef] [PubMed]
- Stoggl, T.L.; Sperlich, B. The training intensity distribution among well-trained and elite endurance athletes. Front. Physiol. 2015, 6, 295. [Google Scholar] [CrossRef] [PubMed]
- Tonnessen, E.; Sylta, O.; Haugen, T.A.; Hem, E.; Svendsen, I.S.; Seiler, S. The road to gold: training and peaking characteristics in the year prior to a gold medal endurance performance. PLoS ONE 2014, 9, e101796. [Google Scholar] [CrossRef] [PubMed]
- Kiely, J. Periodization theory: confronting an inconvenient truth. Sports Med. 2018, 48, 753–764. [Google Scholar] [CrossRef]
- Duking, P.; Fuss, F.K.; Holmberg, H.C.; Sperlich, B. Recommendations for assessment of the reliability, sensitivity, and validity of data from wearable sensors designed for monitoring physical activity. JMIR Mhealth Uhealth 2018, 6, e102. [Google Scholar] [CrossRef]
- Camomilla, V.; Bergamini, E.; Fantozzi, S.; Vannozzi, G. Trends supporting the in-field use of wearable inertial sensors for sport performance evaluation: a systematic review. Sensors 2018, 18, 873. [Google Scholar] [CrossRef]
- Li, R.T.; Kling, S.R.; Salata, M.J.; Cupp, S.A.; Sheehan, J.; Voos, J.E. Wearable performance devices in sports medicine. Sports Health 2016, 8, 74–78. [Google Scholar] [CrossRef]
- Seshadri, D.R.; Li, R.T.; Voos, J.E.; Rowbottom, J.R.; Alfes, C.M.; Zorman, C.A.; Drummond, C.K. Wearable sensors for monitoring the internal and external workload of the athlete. npj Digit. Med. 2019, 2, 71. [Google Scholar] [CrossRef]





|
Evidence domain |
Primary contribution |
Common failure when isolated |
Function in LOAD-R |
| External load | Describes the mechanical or task stimulus applied to the athlete. | High values may be over-interpreted as inherently dangerous or inherently productive. | Defines the L component: what the athlete was asked to absorb. |
| Internal load | Captures perceived or physiological cost of completing the session. | May be inflated by non-training stress, sleep loss, or illness if context is ignored. | Begins the O component: how the athlete experienced the stimulus. |
| Readiness and fatigue |
Indicates whether neuromuscular, perceptual, or autonomic status is stable, elevated, or suppressed. | Single markers can be noisy, insensitive, or sport-specific. | Supports A: classification of adaptive state. |
| Recovery and context |
Places performance output in the broader 24- to 72-h recovery architecture. | Recovery signals can be mistaken for weakness rather than capacity constraints. | Constrains D: the magnitude of progression or reduction. |
| Performance outcome | Tests whether the decision improved task quality or adaptation. | Outcome is often checked too late or detached from the preceding state. | Completes R: re-evaluation and baseline updating. |
| Domain |
Representative variables |
Practical interpretation |
Minimum field implementation |
| External load | Distance, high-speed running, accelerations, decelerations, sprint volume, tonnage, sets, reps, velocity loss. | Defines the imposed stimulus and allows comparison between planned and actual exposure. | Training diary plus sport-relevant load metric. |
| Internal load | sRPE x duration, heart rate, TRIMP, perceived exertion, session difficulty. | Describes the athlete-specific cost of the same external stimulus. | Session RPE collected 15-30 min post-session. |
| Neuromuscular readiness | CMJ height, flight time:contraction time, RSI-modified, jump power, force-time variables. | Identifies acute changes in power, stiffness, or neuromuscular function. | Standardized CMJ protocol 2-3 times weekly. |
| Recovery and wellness |
Sleep, soreness, fatigue, stress, mood, perceived recovery, HRV. | Places training tolerance inside broader recovery capacity. | Short wellness form plus sleep duration/quality. |
| Performance outcome |
Sprint, jump, strength, endurance, sport-specific task quality. | Determines whether the monitoring-guided decision improved the target. | Weekly or block-level performance check. |
| Component | Operational question | Primary data sources |
Default decision relevance |
| L - Load | What stimulus was planned and what was actually completed? | Session plan, GPS, training diary, tonnage, velocity, duration, sRPE-load. | Defines whether progression, maintenance, or reduction is even plausible. |
| O - Organism response | How did the athlete absorb the stimulus? | RPE, HR/HRV, CMJ, wellness, soreness, sleep, mood, technical quality. | Identifies tolerance, strain, or mismatch. |
| A - Adaptive state | What state best explains the current response pattern? | Individual baseline, marker convergence, trend, context, measurement error. | Classifies adaptive, functional overload, underload, uncertainty, or maladaptation. |
| D - Decision | What should be changed today or this week? | Training objective, priority session, competitive calendar, athlete state. | Progress, maintain, modify, deload, recover. |
| R - Re-evaluation | Did the decision improve performance or reduce cost? | Next-day readiness, weekly performance, repeated tests, injury/illness flags. | Updates baselines and improves future decisions. |
| Zone |
Load/readiness pattern |
Interpretation |
Default action |
Risk if misread |
| Green - Adaptive | Moderate/high load with stable or high readiness. | The athlete is tolerating the stimulus. | Maintain or progress according to plan. | Underloading a prepared athlete. |
| Yellow - Functional overload | High load with mild, expected readiness suppression. | Short-term stress may be productive if planned. | Maintain briefly; monitor closely. | Extending overload beyond tolerance. |
| Red - Maladaptive stress | High load with persistent readiness suppression and performance decline. | Fatigue accumulation or unresolved stress is likely. | Reduce intensity/volume; prioritize recovery. | Ignoring early warning signs. |
| Blue - Underload | Low load with high readiness and flat performance. | Stimulus may be insufficient. | Increase load, density, or specificity. | Mistaking freshness for optimal adaptation. |
| Grey - Uncertain | Variable or conflicting signals. | Measurement noise, context, or poor protocol may dominate. | Repeat measure; check sleep, stress, illness, technique. | Acting aggressively on unreliable data. |
| Condition | Likely interpretation | Training decision | Follow-up question |
| High external load + stable readiness + stable output | Productive loading and adequate tolerance. | Maintain planned progression. | Is the next key session protected? |
| High load + reduced CMJ + high soreness |
Neuromuscular fatigue after high mechanical stress. | Reduce sprint/power exposure or convert to technical work. | Does readiness rebound within 24-72 h? |
| Normal external load + unusually high sRPE |
Internal strain mismatch. | Check sleep, stress, illness, nutrition, and heat exposure. | Is this athlete usually honest and consistent with RPE? |
| Low load + high readiness + flat performance |
Insufficient stimulus or poor specificity. | Increase load, intensity, or task specificity. | Is the athlete protected too much? |
| Low load + low readiness | Non-training stress or recovery debt. | Prioritize recovery and contextual assessment. | What happened outside training? |
| Stable load + rising RPE across the week | Accumulating fatigue or reduced tolerance. | Reduce density or insert recovery. | Is performance also declining? |
| Suppressed readiness before low-priority session | Recovery opportunity. | Convert to regenerative or technical session. | Can the high-value session be protected? |
| Suppressed readiness before key session | Risk of low-quality output. | Modify objective or extend warm-up; avoid maximal exposure if convergent signals are poor. | Is the competition calendar forcing risk? |
| Performance improves after deload | Accumulated fatigue confirmed. | Adjust future overload duration. | Was the previous block too long or too dense? |
| Performance does not improve after deload | Deeper issue may be present. | Assess injury, illness, sleep, nutrition, and psychological load. | Is referral or medical review needed? |
| Archetype | Typical pattern | Primary risk | Monitoring priority | Coaching response |
| Fast adapter | Readiness stable; performance improves during progressive load. | Under-challenging the athlete. | Track progression without excessive testing burden. | Progress cautiously and protect recovery. |
| Fatigue accumulator |
Readiness declines; RPE rises; output falls after repeated loading. | Continuing overload beyond useful adaptation. | CMJ, soreness, sleep, RPE trend, next-day performance. | Deload, redistribute intensity, or reduce density. |
| Underloaded athlete |
Readiness high; load low; performance stagnates. | Comfortable non-adaptation. | Performance trend and stimulus specificity. | Increase stimulus or change training content. |
| Context-stressed athlete | Load moderate; wellness poor; readiness variable. | Misattributing life stress to poor motivation. | Sleep, stress, mood, academic/workload, illness flags. | Modify load and address context. |
| Unstable responder |
Large day-to-day variability across markers. | Overreacting to noisy signals. | Protocol consistency and repeated measurements. | Stabilize schedule and measurement conditions. |
| Level | Tools | Best suited for | Decision strength | Main constraint |
| Low-cost | sRPE, wellness, sleep log, training diary, periodic CMJ or jump app. | Amateur clubs, university teams, small performance programs. | Strong if collection is consistent and actions are explicit. | Limited precision and possible self-report bias. |
| Moderate | Jump mat, HR monitor, structured dashboard, simple field tests. | Academies, semi-professional teams, developing high-performance programs. | Allows weekly state tracking and more reliable trends. | Requires staff time and protocol discipline. |
| High-performance | GPS/LPS, force plate, HRV, sleep wearable, integrated AMS. | Elite team sports and professional programs. | Supports individual response modeling and staff communication. | Data overload and false precision. |
| Research-grade | Longitudinal modeling, biomarker sampling, advanced statistics, validation design. | Applied research and framework testing. | Can test predictions and refine thresholds. | Higher cost and complexity. |
| Design element | Rationale | Recommended minimum practice |
| Individual baseline | Group thresholds can hide meaningful within-athlete change. | Report baseline window, reliability, and decision threshold. |
| Measurement error | Small changes may be noise. | Report ICC, CV, SEM, or smallest worthwhile change where possible. |
| Training objective | The same marker has different meaning across session goals. | State whether the goal is adaptation, expression, recovery, or competition specificity. |
| Contextual stress | Sleep, soreness, illness, travel, or academic load can change tolerance. | Collect a concise context/wellness measure. |
| Decision rule | Monitoring without action is incomplete. | State what action was taken when thresholds or zones were reached. |
| Outcome check | The decision must be evaluated. | Report next-day readiness and block-level performance outcomes. |
| Sport specificity | Generic dashboards may miss target performance. | Justify variable selection based on sport and training phase. |
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2026 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).