Incorporating Internal and External Training Load Measurements in Clinical Decision Making After ACL Reconstruction: A Clinical Commentary.

background and purposePoor outcomes after anterior cruciate ligament reconstruction (ACLr), including the relatively high risk of suffering a subsequent ACL injury, suggest the need to optimize rehabilitation and return-to-sport testing. The purpose of this commentary is to introduce clinicians to the concept of monitoring training load during rehabilitation, to review methods of quantifying internal and external loads, and to suggest ways that these technologies can be incorporated into rehabilitation progressions and return-to-sport decisions after anterior ACLr. DESCRIPTION OF TOPIC WITH RELATED EVIDENCE: Quantifying and identifying the effects of training load variables, external (distance, impacts, decelerations) and internal (heart rate, heart rate variability) workload, during rehabilitation can indicate both positive (improved physical, physiological, or psychological capacity) or negative (heightened risk for injury or illness) adaptations and allow for the ideal progression of exercise prescription. When used during return-to-sport testing, wearable technology can provide robust measures of movement quality, readiness, and asymmetry not identified during performance-based testing. DISCUSSION / RELATION TO CLINICAL PRACTICE: Researchers have reported the actual in-game demands of men and women of various ages and competition levels during multi-directional sport. Wearable technology can provide similar variables during rehabilitation, home exercise programs, and during on-field transition back to sport to ensure patients have met the expected fitness capacity of their sport. Additionally, clinicians can use internal load measures to objectively monitor patient's physiological responses to rehabilitation progressions and recovery rather than relying on subjective patient-reported data. LEVEL OF EVIDENCE: 5.