Background Exercises are used to treat temporomandibular disorders (TMD), but they are often assessed with other therapies. Local endurance exercises may alter the resistance to fatigue and pain. Objective To assess the effects of an 8‐week protocol of local endurance exercises of masticatory muscles on muscle excitation, force response, perceived pain and over muscle efficiency. Design Randomised controlled trial. Setting Ambulatory care. Subjects In a placebo randomised controlled trial, 46 women with TMD and oro‐facial pain were randomised into intervention group and placebo group. The intervention group received a protocol of biting endurance exercises, controlled by biofeedback. The placebo group received a placebo (simulated laser therapy). Main Outcome Measures The primary outcomes were collected at baseline, 4 weeks and 8 weeks. Pain was assessed through visual analogue scale (VAS) and pressure pain thresholds (PPT). Bite force was collected by a load cell synchronised with surface electromyography of masticatory muscles, bilaterally. Results Pain scores decreased for both groups, but the intervention group showed lower values at 8 weeks. No differences were noted between groups for PPT, but the results increased for both overtime. Time until fatigue and muscle efficiency were higher in the intervention group vs placebo group in both within‐ and between‐subject analysis. Force increased from 4 to 8 weeks in the PG, without differences between groups. Temporal muscle excitation was higher on 8 weeks compared with baseline for the intervention group, without differences between groups. Conclusion Eight‐week exercise protocol of muscle endurance alleviates the pain and improves the resistance to fatigue and muscle efficiency in TMD subjects.

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Background. It is well known that periods of inactivity generate a loss of muscle strength, a fundamental component of sports performance in soccer. However, little information is available on the decrease in strength levels in professional soccer players after the quarantine lockdown that occurred during the COVID-19 pandemic. Aim. To compare the isokinetic peak torque profiles of professional soccer players from different teams before and after the quarantine period generated by COVID-19. Methods. A retrospective observational study was performed using data collected from two different professional elite-level soccer teams just before and immediately after the COVID-19 quarantine period. One team gave individual instructions to its players for conditioning maintenance at home during the quarantine period, while the other team used regular video calls to maintain the player’s conditioning status on home training. The main outcomes were the mean peak torque of knee extensors and flexors, from concentric and eccentric contractions of each playing position. Analysis. A two-way ANOVA analysis was used to compare peak torque before and after the quarantine period and between both teams’ strategies, showing a statistically significant reduction in eccentric knee flexor peak torque from the team that did not have remote monitoring. Conclusions. Remote monitoring programs are recommended so that athletes are less affected by the deleterious effects of confinement.

Objective: To examine the selective influences of distinct acceleration profiles on the neuromuscular efficiency, force, and power during concentric and eccentric phases of isoinertial squatting exercise. Design: Cross-sectional study. Setting: Biomechanics laboratory of the university. Participants: A total of 38 active adults were divided according to their acceleration profiles: higher (n = 17; >2.5 m/s2) and lower acceleration group (n = 21; <2.5 m/s2). Intervention: All subjects performed squats until failure attached to an isoinertial conic pulley device monitored by surface electromyography of rectus femoris, vastus medialis, vastus lateralis, biceps femoris, and semitendinosus. Main Outcome Measures: An incremental optical encoder was used to assess maximal and mean power and force during concentric and eccentric phases. The neuromuscular efficiency was calculated using the mean force and the electromyographic linear envelope. Results: Between-group differences were observed for the maximal and mean force (Prange = .001–.005), power (P = .001), and neuromuscular efficiency (Prange = .001–.03) with higher significant values for the higher acceleration group in both concentric and eccentric phases. Conclusion: Distinct acceleration profiles affect the neuromuscular efficiency, force, and power during concentric and eccentric phases of isoinertial squatting exercise. To ensure immediate higher levels of power and force output without depriving the neuromuscular system, acceleration profiles higher than 2.5 m/s2 are preferable. The acceleration profiles could be an alternative to evolve the isoinertial exercise.

Purpose. This study assessed the isometric torque, hamstring-to-quadriceps ratio, and jump performance among three age groups of soccer players. Methods. 67 male players were divided by chronological age into the under-17 (U17: n = 29), under-20 (U20: n = 22), and above-20-year (PRO: n = 16) groups. They performed countermovement (CMJ) and squat (SJ) jumps. Also, maximal isometric contractions during knee flexion and extension for right (R-TOR) and left limb (L-TOR) torque were assessed. Hamstrings-quadriceps (H:Q) and CMJ:SJ ratios were determined. Results. Compared with U17 and U20, PRO showed higher CMJ ( = 20% and 14%; both p < 0.01) and SJ ( = 19% and 13%; p < 0.01 and p = 0.02, respectively), and higher absolute R-TOR and L-TOR during knee extension ( = 40% and 58%; both p < 0.01). PRO exhibited higher absolute L-TOR and R-TOR during knee flexion than U17 ( = 22% and 26%; p = 0.04 and p < 0.01, respectively). Between-group differences were not detected in normalized torque, except for knee extension R-TOR (PRO > U17; p = 0.04). Greater differences for quadriceps absolute torque (effect size: 1.37-1.46) were observed in the hamstrings (effect size: 0.30-0.92) between PRO and U17. No differences were found for any H:Q torque ratio, but moderate effect sizes (0.71-0.75) were verified between PRO and the other groups. No differences were found for CMJ:SJ ratio. Conclusions. PRO players are more powerful than U17 and U20. Differences in strength level between PRO and U17/U20 are muscle-dependent. The larger strength development of quadriceps over hamstrings can result in lower isometric H:Q torque ratio for PRO.

Study aim: To compare knee moment profiles of professional soccer players from different playing positions before and after an interseason period. Material and methods: Retrospective study of 467 healthy, professional elite Brazilian soccer players before and after an official championship interseason period during 10-years. Main outcome measures were isokinetic peak moment from knee extensors and flexors from concentric and eccentric contractions. A Two-way ANOVA analysis was used to compare each playing position before and after interseason period. Results: It was found no statistical difference in Ext.CPT (from p = 0.11 to p = 0.97), Ext.EPT (from p = 0.07 to p = 0.85), Flx. CPT (from p = 0.14 to p = 0.90) or Flx.EPT (from p = 0.10 to p = 0.91) between End-Season and Pre-Season evaluations for all playing positions (from Goalkeepers, Defenders, Backsiders, Midfielders and Forwards). Conclusions: Isokinetic peak moment did not have significant differences after an interseason period of 4 to 6 weeks, allowing trainers and coaches to focus their pre-season period on other performance concerns than strengthening.