Effects of Resistance Training Fatigue on Joint Biomechanics

Abstract

Resistance training has been found to have a multitude of benefits. However, when performed with short rest, resistance training can result in substantial fatigue, which may have a negative impact on exercise technique. The purpose of this study is to examine the effects of fatigue from resistance exercise on joint biomechanics to determine what residual movement effects may exist after the workout. Twelve men with at least 6 months of resistance training experience (age 24 ± 4.2 years, height 173.1 ± 3.6 cm, weight 76.9 ± 7.8 kg) performed 5 body weight squats before (pretest) and after (posttest) a highly fatiguing resistance training workout. Lower extremity biomechanics were assessed using a 3-dimensional motion analysis system during these squats. Peak angle, total displacement, and rate were assessed for knee flexion, trunk flexion, hip flexion, hip rotation, and hip adduction. Results showed a significant decrease in peak angle for knee flexion (Pre: 120.28 ± 11.93°, Post: 104.46 ± 9.85°), hip flexion (Pre: -109.42 ± 12.49°, Post: -95.8 ± 12.30°), and hip adduction (Pre: -23.32 ± 7.04°, Post: -17.30 ± 8.79°). There was a significant reduction in angular displacement for knee flexion (Pre: 115.56 ± 10.55°, Post: 103.35 ± 10.49°), hip flexion (Pre: 97.94 ± 10.69°, Post: 90.51 ± 13.22°), hip adduction (Pre: 17.79 ± 7.36°, Post: 11.89 ± 4.34°), and hip rotation (Pre: 30.72 ± 12.28, Post: 20.48 ± 10.12). There was also a significant reduction in displacement rate for knee flexion (Pre: 2.20 ± 0.20, Post: 1.98 ± 0.20), hip flexion (Pre: 1.92 ± 0.20, Post: 1.76 ± 0.27), hip adduction (Pre: -0.44 ± 0.17, Post: -0.31 ± 0.17), and hip rotation (Pre: 0.59 ± 0.23, Post: 0.38 ± 0.21). This study demonstrated that there are lasting residual effects on movement capabilities after a high-intensity short rest protocol. Thus, strength and conditioning coaches must be careful to monitor movements and exercise techniques after such workouts to prevent injury and optimize subsequent exercise protocols that might be sequenced in order.

Kinetic and Kinematic Changes during a 30-Repetition Bout of the Barbell Clean

“…In the authors follow up study [2], participants performed the same fatiguing workout whilst kinematic variables were collected during performance of a loaded squat (75% 1RM). In contrast to the results obtained here and in the authors' previous study [20], Hooper et al [2] reported that the amount of knee flexion increased as the protocol and fatigue progressed. The authors hypothesised that these divergent results were due to the task constraints and a self-preserving behavior adopted by the participants.…”

“…In addition, the results show that as repetitions progressed and fatigue began to accumulate, the amount of knee flexion at the start of the movement continued to decrease. Previous research conducted by Hooper et al [2,20] correspond with the results obtained here and demonstrate that fatigue caused by maximum contractions and task constraints have the potential to affect knee kinematics. In the authors first study [20], it was reported that knee flexion at the beginning of a bodyweight squat decreased after performing a fatiguing workout (pre workout: 118° vs. post workout 105°).…”

“…Previous research conducted by Hooper et al [2,20] correspond with the results obtained here and demonstrate that fatigue caused by maximum contractions and task constraints have the potential to affect knee kinematics. In the authors first study [20], it was reported that knee flexion at the beginning of a bodyweight squat decreased after performing a fatiguing workout (pre workout: 118° vs. post workout 105°). The authors suggested that the altered movement pattern occurred in response to fatigue as a means of reducing the amount of work required and therefore the energy demand [20].…”

“…In the authors first study [20], it was reported that knee flexion at the beginning of a bodyweight squat decreased after performing a fatiguing workout (pre workout: 118° vs. post workout 105°). The authors suggested that the altered movement pattern occurred in response to fatigue as a means of reducing the amount of work required and therefore the energy demand [20]. In the authors follow up study [2], participants performed the same fatiguing workout whilst kinematic variables were collected during performance of a loaded squat (75% 1RM).…”

Overuse Injuries Associated with Mountain Biking: Is Single-Speed Riding a Predisposing Factor?

“…The relationship between excessive fatigue and a corresponding progressive change in biomechanics during athletic performance is well documented. Studies in which athletes are physically pushed beyond lactate thresholds or to voluntary exhaustion clearly demonstrate that these levels of fatigue are associated with significant changes in biomechanics [22][23][24][25][26]. Furthermore, there is considerable evidence that excessive fatigue has the same effect on cycling mechanics [21,[27][28][29][30].…”