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Introduction: The aim of this study was to evaluate the intra and inter-rater and inter-analyzer reliability of neuromuscular variables and functional tests. Methods: Cross-sectional crossover design. Two independent raters and analyzers evaluated twenty-two healthy subjects. Knee-extensor strength was assessed from three maximal voluntary isometric contractions. Muscle activation was obtained from the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) muscles. VL and RF muscles' architecture [fascicle length (FL), pennation angle (PA), muscle thickness (MT)] was obtained at rest by ultrasound. The time from five sit-to-stand (STS) trials, and the distance from the 6-min walk test (6MWT) were obtained. Intraclass correlation coefficient was determined and classified as strong (r ¼ 0.75e1.00), moderate (r ¼ 0.40e0.74), and weak (r < 0.40). Results: Strong intra-rater reliability values were observed for strength (r ¼ 0.97), muscle activation [VL (r ¼ 0.91

Purpose: This study aimed to determine whether triceps surae’s muscle architecture and Achilles tendon parameters are related to running metabolic cost (C) in trained long-distance runners.Methods: Seventeen trained male recreational long-distance runners (mean age = 34 years) participated in this study. C was measured during submaximal steady-state running (5 min) at 12 and 16 km h–1 on a treadmill. Ultrasound was used to determine the gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and soleus (SO) muscle architecture, including fascicle length (FL) and pennation angle (PA), and the Achilles tendon cross-sectional area (CSA), resting length and elongation as a function of plantar flexion torque during maximal voluntary plantar flexion. Achilles tendon mechanical (force, elongation, and stiffness) and material (stress, strain, and Young’s modulus) properties were determined. Stepwise multiple linear regressions were used to determine the relationship between independent variables (tendon resting length, CSA, force, elongation, stiffness, stress, strain, Young’s modulus, and FL and PA of triceps surae muscles) and C (J kg–1m–1) at 12 and 16 km h–1.Results: SO PA and Achilles tendon CSA were negatively associated with C (r2 = 0.69; p &lt; 0.001) at 12 km h–1, whereas SO PA was negatively and Achilles tendon stress was positively associated with C (r2 = 0.63; p = 0.001) at 16 km h–1, respectively. Our results presented a small power, and the multiple linear regression’s cause-effect relation was limited due to the low sample size.Conclusion: For a given muscle length, greater SO PA, probably related to short muscle fibers and to a large physiological cross-sectional area, may be beneficial to C. Larger Achilles tendon CSA may determine a better force distribution per tendon area, thereby reducing tendon stress and C at submaximal speeds (12 and 16 km h–1). Furthermore, Achilles tendon morphological and mechanical properties (CSA, stress, and Young’s modulus) and triceps surae muscle architecture (GM PA, GM FL, SO PA, and SO FL) presented large correlations with C.

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Background The combined effects of low-level laser therapy and neuromuscular electrical stimulation on knee osteoarthritis have yet to be analysed. This study aimed to determine the individual and combined effects of laser therapy and electrical stimulation on muscle activation and pain in older people with knee osteoarthritis. Methods A total of 45 women aged 60–75 years with knee osteoarthritis were randomised into three groups to receive stimulation, laser or stimulation plus laser therapy. All three groups underwent a 4-week control period (without intervention) followed by an 8-week intervention period. The effects of the interventions on muscle inhibition, electrical activity and pain were analysed. Findings There was a decrease in muscle inhibition (effect size ≥0.6) and a reduction in pain (effect size >1.2) in all three groups. All therapies generated an increase in electrical activity (effect size 0.1–0.5). Conclusions Laser alone or in combination with electrical stimulation promoted similar increases in muscle activation and pain relief.

Rebounding fitness class became popular due to the supposed capacity of minimize the impact forces on the body of participant. However, no studies about impact forces during rebound exercise class have been found. Thus, the aim of this study was to assess the impact forces produced during a series of traditional rebounding exercises and present a categorization based on impact force parameters. Sixty instructors of rebound exercise performed various rebound exercises on a standard mini-trampoline, which was optimized with six load cells. The load cells were used to assess the impact parameters (peak and loading rate of the ground reaction force). One-way ANOVA was used to compare the exercises (α = 0,05). As results, we noted that when peak force is used to assess impact, the most of the rebound exercises are classified as low (<3xPC) and high impact (>4xPC); while when rate loading is used, most of the exercises are considered as moderate (20-30x PC/s) and high impact (<20x PC/s). Thus, each evaluated impact parameter results in a different rebound exercise categorization. The selection of progression of rebounding exercises during a fitness class should take in consideration the peak and loading rate values and its possible effects on the musculoskeletal system.