Low-level laser therapy (LLLT) has shown efficacy in muscle bioenergetic activation and its effects could influence the mechanical performance of this tissue during physical exercise. This study tested whether endurance training associated with LLLT could increase human muscle performance in isokinetic dynamometry when compared to the same training without LLLT. The primary objective was to determine the fatigue index of the knee extensor muscles (FIext) and the secondary objective was to determine the total work of the knee extensor muscles (TWext). Included in the study were 45 clinically healthy women (21 ± 1.78 years old) who were randomly distributed into three groups: CG (control group), TG (training group) and TLG (training with LLLT group). The training for the TG and TLG groups involved cycle ergometer exercise with load applied to the ventilatory threshold (VT) for 9 consecutive weeks. Immediately after each training session, LLLT was applied to the femoral quadriceps muscle of both lower limbs of the TLG subjects using an infrared laser device (808 nm) with six 60-mW diodes with an energy of 0.6 J per diode and a total energy applied to each limb of 18 J. VT was determined by ergospirometry during an incremental exercise test and muscle performance was evaluated using an isokinetic dynamometer at 240°/s. Only the TLG showed a decrease in FIext in the nondominant lower limb (P = 0.016) and the dominant lower limb (P = 0.006). Both the TLG and the TG showed an increase in TWext in the nondominant lower limb (P < 0.001 and P = 0.011, respectively) and in the dominant lower limb (P < 0.000 and P < 0.000, respectively). The CG showed no reduction in FIext or TWext in either lower limb. The results suggest that an endurance training program combined with LLLT leads to a greater reduction in fatigue than an endurance training program without LLLT. This is relevant to everyone involved in sport and rehabilitation.

Abstract-We investigated the role of an evidence-based integrated group rehabilitation program on the treatment of patients with knee osteoarthritis (KOA). This was a two-group, randomized controlled, 8 wk trial with 41 patients with moderate to very severe KOA. Patients were assigned to an intervention group (IG) or control group (CG). After both groups had received a self-management education program, IG participants underwent a rehabilitation program, including educational aspects about KOA followed by exercises. CG participants received only general health orientation about KOA during this period. The outcome measures were the Lequesne algofunctional index; 36-Item Short Form Health Survey (SF-36); and chair-stand, sit-and-reach, timed up-and-go, and 6-minute walk tests. Analysis of covariance revealed significant postintervention improvements of IG participants compared with CG participants (p < 0.05) on Lequesne total score and pain and function subdomains; SF-36 physical function, role physical, bodily pain, general health, vitality, and role emotional subdomains; and performance assessed by chair-stand, timed up-and-go, and 6-minute walk tests. Focusing on the primary outcome (Lequesne total score), the mean +/-standard deviation after 8 wk was 5.50 +/-2.98 for the IG and 7.87 +/-3. https://clinicaltrials.gov/ct2/show/ NCT01850862?term=NCT01850862&rank=1

The aim of this randomized double-blind placebo-controlled study was to investigate the effect of low-level laser therapy (LLLT) on markers of muscle damage (creatine kinase (CK) and strength performance) in the biceps brachii. Twenty-two physically active men were randomized into two groups: placebo and laser. All volunteers were submitted to an exercise-induced muscle damage protocol for biceps brachii (biceps curl, 10 sets of 10 repetitions with load of 50% of one-repetition maximum test (1RM)). Active LLLT (808 nm; 100 mW; 35.7 W/cm(2), 357.14 J/cm(2) per point, energy of 1 J per point applied for 10 s on four points of the biceps brachii belly of each arm) or placebo was applied between the sets of the biceps curl exercise. CK activity and maximum strength performance (1RM) were measured before, immediately after, 24, 48, and 72 h after the exercise-induced muscle damage protocol. There was an increase in CK activity after the muscle damage protocol in both groups; however, this increase was attenuated in the laser group compared to the placebo group at 72 h (placebo = 841 vs. laser = 357%; p < 0.05). Maximum strength performance was decreased immediately after the muscle damage protocol in both groups (p < 0.05), but at 24, 48, and 72 h, and it returned to the baseline level in both groups. In conclusion, the LLLT attenuated CK activity 72 h after the muscle damage protocol but did not have a positive effect on the recovery of strength performance.

Barbosa, GM, Trajano, GS, Dantas, GAF, Silva, BR, and Vieira, WHB. Chronic effects of static and dynamic stretching on hamstrings eccentric strength and functional performance: A randomized controlled trial. J Strength Cond Res 34(7): 2031–2039, 2020—The purpose of this study was to investigate the effect of static or dynamic stretching training program on hamstrings eccentric peak torque and functional performance. Forty-five active healthy men were randomly allocated into 3 groups (n = 15 per group): no stretching (control), static stretching (3 sets of 30 seconds), and dynamic stretching (3 sets of 30 repetitions). Static and dynamic stretching protocols on the hamstring muscles were performed 3 times a week until complete 10 sessions. Isokinetic knee flexor eccentric peak torque (60°·s−1), triple hop distance, and modified 20-m sprint time were assessed in a random order before and after stretching training. A mixed-design analysis of variance was performed, with an alpha level of 0.05. There was a significant decrease of eccentric peak torque (p ≤ 0.0001, −15.4 ± 10.4%, within-group effect size: 1.03) after static stretching training. The static stretching training reduced eccentric torque when compared with no stretching (−7.6 ± 21.7%, between-group effect size: 0.50) and dynamic stretching (−7.8 ± 29.8%, between-group effect size: 0.51). Moreover, the reached distance on triple hop test was also reduced after static stretching protocol (p = 0.009, −3.7 ± 4.1%, within-group effect size: 0.29). These findings suggest that static stretching training is sufficient to produce meaningful reductions on hamstrings eccentric torque and functional performance. Based on the results of this study, caution should be taken when prescribing of static stretching training in isolation when the purpose is to improve performance, and indirectly, to prevent hamstring strain injuries due to its possible negative effects on hopping performance and knee flexor eccentric torque.

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