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Background and objective: Type of physical activity may influence morphological and muscular asymmetries in the young population. However, less is known about the size of this effect when comparing various sports. The aim of this study was to identify the degree of bilateral asymmetry (BA) and the level of unilateral ratio (UR) between isokinetic strength of knee extensors (KE) and flexors (KF) among athletes of three different types of predominant locomotion in various sports (symmetric, asymmetric and hybrid). Material and methods: The analyzed group consisted of young elite athletes (n = 50). The maximum peak muscle torque of the KE and KF in both the dominant (DL) and non-dominant (NL) lower limb during concentric muscle contraction at an angular velocity of 60°·s-1 was measured with an isokinetic dynamometer. Results: Data analysis showed a significant effect of the main factor (the type of sport) on the level of monitored variables (p = 0.004). The type of sport revealed a significant difference in the bilateral ratio (p = 0.01). The group of symmetric and hybrid sports achieved lower values (p = 0.01) of BA in their lower limb muscles than those who played asymmetric sports. The hybrid sports group achieved higher UR values (p = 0.01) in both lower limbs. Conclusions: The results indicate that sports with predominantly symmetrical, asymmetrical, and hybrid types of locomotion affected the size of the BA, as well as the UR between KE and KF in both legs in young athletes. We recommend paying attention to regular KE and KF strength diagnostics in young athletes and optimizing individual compensatory exercises if a higher ratio of strength asymmetry is discovered.

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[Purpose] To compare flexion and extension peak torque of patients with nonspecific-chronic low back pain who were classified as directional preference subgroups, and their matched healthy controls. [Participants and Methods] Fifty male volunteers (25 with non-specific chronic low back pain and 25 healthy-matched controls) consented to participate. The investigator collected all demographic data, hips, knees and spinal mobility in addition to the peak torque using the Biodex isokinetic dynamometer. The measurement protocol consisted of 2 sets of 10 consecutive flexion-extension efforts performed at 120°/sec and 60°/sec angular velocity. A two minutes rest period was given between sets. The preset 50° range of motion included 20°(+20°) of trunk extension and 30°(-30°) of trunk flexion. [Results] A 2 × 2 mixed-design ANOVA showed a significant group X isokinetic velocity interaction. The main effect of isokinetic velocity was also significant. In reference to the peak torque of the flexors of the trunk, the main effect of group was significant. [Conclusion] The extension peak torque significantly depends on the velocity of the isokinetic dynamometer; however the flexion peak torque significantly depends on the participants' group attribution.

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@#Introduction: This study investigated the effect of combined plant-based protein supplementation and resistance training on muscular strength, blood markers of protein catabolism, immune function, and bone metabolism in sedentary adult males. Methods: In this randomised, double-blinded study, 28 healthy males aged 19 – 29 years old were equally assigned into four groups: a combined plant-based protein with resistance training (PBPEX), plant-based protein alone (PBP), resistance training alone (EX) and control (C). Mode of resistance training was flat barbell press, machine shoulder press, wide grip lateral pull-down, seated cable row, barbell back squat, leg press and leg extension. The 8-week resistance training involved three sets of 60-70% of one-repetition maximum (1-RM) at 4-6 repetition/set/mode per session, three sessions/week. Participants in PBPEX and PBP groups consumed a plant-based protein supplement consisted of 9.8 g soy and pea protein for seven days/week. Results: PBPEX showed significant increases (p<0.01) in the knee and shoulder flexion peak torque compared to EX groups, respectively. PBP showed a significantly higher level (p<0.05) of serum urea, and blood urea nitrogen (BUN) compared to other groups. There were no changes in immune function and bone metabolism markers between pre- and post-exercise in all groups. Conclusions: These findings implied that a combination of plant-based protein supplementation and resistance training elicited greater beneficial effects on muscular strength than resistance training alone and plant-based protein supplementation alone. Therefore, combined plant-based protein with resistance training may be recommended in planning exercise and nutritional programme for sedentary male adults.

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OBJECTIVES: To investigate any differences in muscle architecture (fascicle angle, fascicle length, and muscle thickness) and muscle strength in people of different ages with and without knee osteoarthritis (OA). METHODS: This is a cross-sectional study conducted with 40 individuals with and 40 without knee OA. Four groups were analyzed, middle-aged OA group (KL II/III) aged 40-50 years (n = 20), middle-aged healthy (H) group aged 40-50 years (n = 20), older OA group (KL II/III) aged 70 years and over (n = 20), and older H group, aged 70 years and over (n = 20). Outcomes analyzed were isometric and isokinetic peak torque of knee extensors, level of physical activity, self-reported pain level, and vastus lateralis fascicle length, fascicle angle, and muscle thickness assessed by ultrasound. One-way ANOVA was used to identify differences between groups, followed by the Tukey post hoc test. RESULTS: There were no differences between the middle-aged OA group and older H group for any variables. The older OA group presented the smallest muscle architecture parameters and worst isometric and concentric peak torques compared to the other three groups (p < 0.001). In contrast, the middle-aged H group presented the largest muscle architecture parameters and was the strongest group compared to the others (p < 0.001). CONCLUSIONS: The presence of knee OA is associated with early muscular changes and seems to intensify these thigh changes that are similar to the effects of the aging process.

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The aim of this study was to investigate the relationship between in quadriceps and hamstrings inter-limb strength asymmetry and change of direction, sprinting and jumping abilities in U21 elite soccer players. Twenty-seven soccer players volunteered for this study. Isokinetic quadriceps and hamstrings peak torque was measured at high and low angular velocities, both in concentric and eccentric modalities. Performance in agility T-test, 20 + 20 m shuttle-test, 10 m and 30 m sprint, squat jump (SJ) and counter-movement jump (CMJ), were measured. Overall, time on agility T-test and 20 + 20 m shuttle-test was moderately and positively correlated with the quadriceps and hamstrings inter-limb eccentric peak torque asymmetry, both at high and low angular velocities. In addition, time on 10 m and 30 m sprints was moderately and positively correlated with the hamstrings inter-limb high-velocity concentric peak torque asymmetry. SJ and CMJ showed trivial to small correlations with hamstrings and quadriceps inter-limb peak torque asymmetry. The present results provide further information insight the role of lower-limb muscle strength balance in COD, sprinting and jumping performance.

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PURPOSE: High level of physical activity (PA) is associated with great muscle strength and high fracture risk. This prospective controlled population-based study evaluated how a pediatric PA intervention program influenced muscle strength and fracture risk. METHODS: We carried out a school-based exercise intervention program with 200 min of PA per week for 5 years in 335 girls and 408 boys aged 6-9 years at study start. An age-matched control cohort including 756 girls and 782 boys continued with 60 min of PA per week. We registered fractures during the study period and calculated rate ratio. In a sub-sample, including 74 girls and 107 boys in the intervention and 51 girls and 54 boys in the control group, we measured knee flexion and extension strength by a computerized dynamometer and leg composition by dual energy X-ray absorptiometry. Group comparisons were adjusted for differences in age, baseline value for the measured parameter and changes in height. RESULTS: Children in the intervention group had a rate ratio to sustain a fracture of 1.03 (0.78, 1.36) (mean and 95 % confidence interval) (p = 0.79). The annual gain in flexion peak torque muscle strength was greater in both girls (at 60°/s) [1.1 Nm (0.5, 1.8), p < 0.01] and boys (at 180°/s) [0.7 Nm (0.1, 1.2), p < 0.05] in the intervention than in the control group, while leg composition was similar. CONCLUSION: Increased PA during a 5-year period, starting in the pre-pubertal period, improves the gain in muscle strength without affecting the fracture risk.

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Objective To determine key muscles during muscle strength training of patients with knee osteoarthritis (KOA) by studying the correlation of KOA symptoms and disease stages with knee extensor/flexor strength. Methods Ninety-nine community volunteers were recruited and stratified into healthy group, single KOA group, and bilateral KOA group. The relationship between isokinetic extensor/flexor strength and KOA symptom, full-body aerobic exercise capacity, joint function were analyzed by knee isokinetic muscle strength test, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), 6-minute walk test, and CS-30 test. ResultsKnee isokinetic extensor peak torque of the symptomatic leg was significantly lower than that of the asymptomatic leg in single KOA group. There were significant differences in knee isokinetic extensor/flexor peak torque of both the severe and mild symptomatic leg in bilateral KOA group. Knee isokinetic extensor peak torque in bilateral KOA group was significantly lower than that in healthy group. Knee isokinetic extensor/flexor peak torque of KOA patients was positively related to 6-minute walk test, CS-30 test, while negatively related to age. Knee isokinetic extensor peak torque was negatively related to pain score and physical function score of WOMAC. Conclusions Both knee extensor and flexor strength are related to KOA. Therefore, during KOA rehabilitation therapies, muscle training for knee extensors (particularly quadriceps femoris muscles) and knee flexors (hamstring muscles, gastrocnemius muscles) need to be valued.