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Kazunori Yasuda, Harukazu Tohyama and Masayuki Inoue

Studies on the effect of posterior cruciate ligament (PCL) injury on muscle performance have demonstrated that the normal PCL accommodates sensory nerve endings with capabilities that provide the central nervous system with information about characteristics of movement and position-related stretches of the PCL. Concerning the effect of PCL injury on performance of the quadriceps and hamstrings, there is disagreement in the literature. If there is an effect in the PCL-deficient knee, it is not as simple as that in the anterior cruciate ligament (ACL)-deficient knee. Electromyographic studies have demonstrated that the gastrocnemius muscle is significantly activated during walking and isokinetic motion in the involved knee, as compared with the uninvolved knee. Results of a gait-analytic study suggested that there are significant differences in gait cycle between PCL-deficient and normal knees. These phenomena might be part of the compensatory mechanism in PCL-deficient knees, but the data on the effect of PCL injury on muscle performance remain insufficient at the present time.

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Jeffrey R. Doeringer, Megan Colas, Corey Peacock and Dustin R. Gatens

Key Points • Cold-water immersion affected an individual’s speed 48 hr later. • Perception of pain/soreness showed to be significant after 24 hr. • Postexercise cold-water immersion does not improve muscle performance recovery. For decades, cold-water immersion has been used to treat injuries

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Wonjae Choi and Seungwon Lee

video recording, which enable the use of different exercises in various environments. Therefore, the present study aimed to investigate the effects of a virtual kayak paddling (VKP) exercises using real-world video recording on postural control, muscle performance, and cognitive function in older adults

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Matthew R. Doyle, Michael J. Webster and Loran D. Erdmann

The purpose of this study was to investigate the effect of oral allithiamine administration on isokinetic parameters of muscle performance and lactate accumulation prior to, during, and in recovery from isokinetic exercise. A double-blind, counterbalanced, crossover experimental design utilizing aBiodex System 2 Isokinetic Dynamometer was used to test 15 healthy college students. Subjects orally ingested either 1 g · day1 of a thiamin derivative, allithiamine, or a placebo for 5 days and then performed six exercise sets of knee extension and flexion. ANOVA revealed no significant differences between treatment conditions in peak torque, mean peak torque, average power, or total work performed (p > .05). Likewise, lactate accumulation was not significantly different between treatment conditions at any measurement point (p > .05). The absence of significant differences suggests that oral allithiamine administration does not enhance isokinetic parameters of muscle performance or lactate accumulation prior to, during, and following isokinetic exercise.

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Moisés de Hoyo, Alejandro Álvarez-Mesa, Borja Sañudo, Luis Carrasco and Sergio Domínguez

Context:

Kinesio taping (KT) is a new taping technique increasingly used in sports medicine to improve muscle performance; however, its real effect is not entirely known.

Objective:

To assess the immediate effects of KT on muscle performance in young healthy elite soccer players.

Design:

Crossover study.

Setting:

University laboratory.

Participants:

Eighteen young elite soccer players voluntarily participated in the study (mean ± SEM: age 18.20 ± 2.45 y, height 1.76 ± 3.56 m, body mass 65.25 ± 3.76 kg, body-mass index 20.12 ± 1.25 kg/m2).

Interventions:

Each subject completed 2 different protocols, with and without KT. Interventions were performed in a random order, with a washout period between conditions of 1 wk.

Main Outcome Measures:

Outcome measures included tensiomyographic response in the vastus lateralis and vastus medialis, power output with 30 and 50 kg, countermovement jump, and 10-m sprint.

Results:

Data showed no significant differences for any of the outcomes analyzed between interventions.

Conclusions:

KT does not produce a short-term improvement in muscle performance in young elite soccer players.

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Sven Rees, Aron Murphy and Mark Watsford

This study was designed to investigate the effects of vibration on muscle performance and mobility in a healthy, untrained, older population. Forty-three participants (23 men, 20 women, 66–85 y old) performed tests of sit-to-stand (STS), 5- and 10-m fast walk, timed up-and-go test, stair mobility, and strength. Participants were randomly assigned to a vibration group, an exercise-without-vibration group, or a control group. Training consisted of 3 sessions/wk for 2 mo. After training, the vibration and exercise groups showed improved STS (12.4%, 10.2%), 5-m fast walk (3.0%, 3.7%), and knee-extension strength (8.1%, 7.2%) compared with the control (p < 0.05). Even though vibration training improved lower limb strength, it did not appear to have a facilitatory effect on functional-performance tasks compared with the exercise-without-vibration group. Comparable mobility and performance changes between the experimental groups suggest that improvements are linked with greater knee-extension strength and largely attributed to the unloaded squats performed by both exercise groups.

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Rob Duffield, Monique King and Melissa Skein

Purpose:

This study investigated the effects of hot conditions on the acute recovery of voluntary and evoked muscle performance and physiological responses following intermittent exercise.

Methods:

Seven youth male and six female team-sport athletes performed two sessions separated by 7 d, involving a 30-min exercise protocol and 60-min passive recovery in either 22°C or 33°C and 40% relative humidity. The exercise protocol involved a 20-s maximal sprint every 5 min, separated by constant-intensity exercise at 100 W on a cycle ergometer. Maximal voluntary contraction (MVC) and a resting evoked twitch (Pf) of the right knee extensors were assessed before and immediately following exercise and again 15, 30, and 60 min post exercise, and capillary blood was obtained at the same time points to measure lactate, pH, and HCO3. During and following exercise, core temperature, heart rate and rating of perceived exertion (RPE) were also measured.

Results:

No differences (P = 0.73 to 0.95) in peak power during repeated sprints were present between conditions. Post exercise MVC was reduced (P < .05) in both conditions and a moderate effect size (d = 0.60) indicated a slower percentage MVC recovered by 60 min in the heat (83 ± 10 vs 74 ± 11% recovered). Both heart rate and core temperature were significantly higher (P < .05) during recovery in the heat. Capillary blood values did not differ between conditions at any time point, whereas sessional RPE was higher 60 min post exercise in the heat.

Conclusions:

The current data suggests that passive recovery in warm temperatures not only delays cardiovascular and thermal recovery, but may also slow the recovery of MVC and RPE.

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Che-Hsiu Chen, Tsun-Shun Huang, Huei-Ming Chai, Mei-Hwa Jan and Jiu-Jenq Lin

Context:

Recent studies have shown that the static stretch (SS) may adversely affect leg-muscle performance.

Objectives:

The authors examined the short-term effects of 2 stretching exercises on hamstrings muscle before and after exercise.

Design:

Crossover.

Setting:

Laboratory.

Participants:

9 healthy, physically active men.

Interventions:

There were 3 protocols in a randomized order with a 7-d interval: nonstretching (CON protocol), hamstrings static stretching (SS) with proprioceptive neuromuscular facilitation (PNF), and SS with kinesio-taping application on the hamstrings.

Main Outcome Measures:

Outcome measures included first-felt and maximum tolerant-felt range of motion (FROM and TROM), maximal knee-flexion peak torque (PT) at 180°/s, and hamstrings muscle stiffness.

Results:

Groups were not different at prestretching in terms of hamstrings flexibility, PT, and muscle stiffness. At poststretching, both stretching protocols showed significant increases in FROM and TROM (P < .05). Stiffer hamstrings muscle and decreased PT were found in both SS+PNF and CON protocols (P < .05). However, there was no significant difference in the SS+Taping protocol (P > .05).

Conclusion:

The stretching protocols improve hamstrings flexibility immediately, but after exercise hamstrings peak torque is diminished in the SS+PNF but not in the SS+Taping group. This means that SS+Taping can prevent negative results from exercise, which may prevent muscle injury.

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Shaun O’Leary, Carlijn Hoogma, Øystein Molland Solberg, Sara Sundberg, Ashley Pedler and Luke Van Wyk

healthy individuals. Such deficits in muscle performance are feasible given the evidence of atrophy, 14 – 16 altered fiber composition, 17 and altered coordination 18 – 22 within the neck muscles of individuals with idiopathic neck pain. These impairments may potentially impact the capacity of neck

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James W. Youdas, Erica F. Loder, Jody L. Moldenhauer, Christine R. Paulsen and John H. Hollman

Context:

Hip-abductor weakness is associated with many lower extremity injuries. A simple procedure to assess hip-abductor performance is necessary in patient populations.

Objective:

To describe the change in pelvic-on-femoral position of the stance limb before and after 45 seconds of resisted sidestepping.

Design:

Cross-sectional comparative.

Setting:

Laboratory.

Participants:

24 healthy women (24.6 ± 3.5 years) and 14 healthy men (24.5 ± 3.0 years).

Main Outcome Measures:

Pelvic-on-femoral position in degrees in single-leg stance before and after 45 seconds of resisted sidestepping.

Results:

The difference between the baseline and postexercise measurements for both men and women was significant (P < .05). The effect of the resisted-sidestepping exercise on the hip abductors was not statistically different between men and women.

Conclusions:

Forty-five seconds of resisted sidestepping using an elastic band produced a change in pelvic-on-femoral position in healthy adults. This test might be useful to detect impaired performance in hip abductors of patients with injury elsewhere in the musculoskeletal system.