Isokinetics and Exercise Science - Volume Pre-press, issue Pre-press
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Isokinetics and Exercise Science (IES) is an international journal devoted to the study of theoretical and applied aspects of human muscle performance. Since isokinetic dynamometry constitutes the major tool in this area, the journal takes a particular interest in exploring the considerable potential of this technology.
Isokinetics and Exercise Science publishes studies associated with the methodology of muscle performance especially with respect to the issues of reproducibility and validity of testing, description of normal and pathological mechanical parameters which are derivable from muscle testing, applications in basic research topics such as motor learning paradigms and electromyography. The journal also publishes studies on applications in clinical settings and technical aspects of the various measurement systems employed in human muscle performance research.
Isokinetics and Exercise Science welcomes submissions in the form of research papers, reviews, case studies and technical reports from professionals in the fields of sports medicine, orthopaedic and neurological rehabilitation and exercise physiology.
Abstract: INTRODUCTION: Cycling has been the subject of numerous studies. Among these, measuring muscular performance during cycling has attracted much interest. OBJECTIVE: To investigate the relationship between Wattbike ® and isokinetic findings in a group of cyclists. METHODS: Thirty-seven male cyclists performed a 30-s anaerobic power test on a Wattbike ® and then were tested concentrically for knee extensor and flexor strength using isokinetic dynamometry. RESULTS: There was a positive fair-to-moderate correlation between the peak moment, peak power, and total work derived from…the Wattbike ® and the respective parameters evaluated isokinetically. CONCLUSION: While the findings exclude interchangeability of the two methods, the fact that total work is the most closely associated parameter among the measurements highlights its importance as an outcome measure in muscle performance in cyclists.
Abstract: BACKGROUND: Postactivation potentiation (PAP) is an acute and temporary enhancement of muscular performance resulting from previous muscular contraction. Extensive research exists examining the PAP effect after a heavy resistance exercise but there is limited research examining the PAP effect after a plyometric stimulus to the pre-competition practices (e.g., warm-up) of well-trained athletes. OBJECTIVE: The purpose of this study was to investigate the acute effects of plyometric warm-up with different box heights on sprint and agility performance in national-level field hockey athletes at recovery time of immediately, 5 minutes and 10 minutes. METHODS: In…a randomized crossover design, ten male national-level field hockey athletes performed 30-m sprint (with 10-m split) and agility test at baseline, immediately (∼ 15 sec), 5 minutes and 10 minutes after a high-intensity plyometric warm-up (HIPW), a low-intensity plyometric warm-up (LIPW) and a control trial (CT). RESULTS: Mean 10-m sprint times, 30-m sprint times and agility times were similar between trials at baseline (p > 0.05). Significant trial x time interactions (p ⩽ 0.05) were observed for 10-m sprint time, 30-m sprint time and agility time. 10-m sprint times were significantly decreased after HIPW at all time-points and LIPW at immediately time-point, relative to baseline (p ⩽ 0.05). HIPW 10-m sprint times were faster at all time-points and LIPW sprint time was faster at 10 minutes when compared with CT (p ⩽ 0.05). Thirty-meter sprint times were significantly decreased after HIPW and LIPW at all time-points, relative to baseline (p ⩽ 0.05). HIPW 30-m sprint times at all time-points and LIPW at both the 5 and 10 minute time-points were faster than CT (p ⩽ 0.05). Agility times were significantly decreased after HIPW at all time-points and LIPW at both the immediately and 5 minutes time-points, relative to baseline (p ⩽ 0.05). HIPW and LIPW agility times were faster than CT, at all time-points (p ⩽ 0.05). CONCLUSIONS: Both HIPW and LIPW may be effective in enhancing the pre-training or pre-competition practices in off-season for national-level field hockey athletes. However, the individualization of HIPW is highly recommended in order to maintain PAP effects for 10-m sprint times, 30-m sprint times and agility times throughout the 10 minutes when compared to LIPW.
Keywords: Post-activation potentiation, stretch-shortening cycle, depth jump, speed, team sport
Abstract: BACKGROUND: Few studies have examined sex differences in performance fatigability and the bilateral deficit in a dynamic modality. OBJECTIVES: The purpose of this study was to examine: 1) Leg-, mode-, and sex-specific differences in performance fatigability during maximal, dynamic leg extension muscle actions and; 2) the time course of fatigue-induced changes in the bilateral deficit for both men and women. METHODS: Eleven men and 11 women participated in 3 test visits consisting of 50 maximal, concentric, isokinetic leg extensions at 60 ∘ /s. Each visit was randomized to perform either unilateral…right leg only (RL), unilateral left leg only (LL), or bilateral (BL) leg extensions. RESULTS: The BL performance fatigability was significantly (p < 0.001) less than RL and LL. Both men and women demonstrated significant (p < 0.001) declines in moment and an attenuation of the bilateral deficit throughout the fatiguing task. There were no differences between sex for performance fatigability (p = 0.128) or the bilateral deficit (p = 0.102). CONCLUSIONS: Unilateral muscle actions were more susceptible to fatigue than BL muscle actions. Men exhibited an earlier decline in moment than women, however, men and women exhibited similar magnitudes and patterns of decline in the bilateral deficit.
Keywords: Performance fatigability, bilateral deficit, dynamic, isokinetic, sex differences, fatigue
Abstract: BACKGROUND: The cardiovascular response to resistance training is influenced by different variables such as intensity and volume. OBJECTIVE: To compare the effects of resistance training sessions differing in level of effort on blood pressure and arterial stiffness. METHODS: Thirty-two men performed 3 sets at 75% of 1-RM during the bench press and squat exercises to failure (n = 16; high-effort group), or performing half of the maximum possible number of repetitions per set (n = 16; low-effort group). Blood pressure (systolic blood pressure…[SBP], diastolic blood pressure [DBP], and mean arterial pressure [MAP]) and arterial stiffness (pulse wave velocity [PWV]) were measured before training (Pre), immediately after training (Post 1), 5 minutes after training (Post 2), and 24 hours after training (Post 3). RESULTS: A main effect of time (p ⩽ 0.012) was observed for all variables due to higher values at Post 1 compared to Post 2 (effect size [ES] range: 0.34–1.37) and Post 3 (ES range: 0.37–0.92). When compared to Pre, increases higher than a ES of 0.20 were observed for the high-effort group compared to the low-effort group at all time points. CONCLUSIONS: Training to failure should be discouraged to avoid acute increases in blood pressure and arterial stiffness.
Keywords: Cardiovascular disease, exercise prescription, pulse wave velocity, velocity based training
Abstract: BACKGROUND: Small-sided games are a popular training method that have shown its effectiveness in improving athletic performance in football players. OBJECTIVE: To compare the acute physiological and neuromuscular responses and time-motion characteristics during small-sided games played with and without wildcard players. METHODS: Sixteen amateur male football players completed two small-sided games protocol: 4-a-side and 4-a-side with wildcard players. Time-motion characteristics during games, muscular performance parameters before and after small-sided games protocols, physiological response in terms of heart rate and muscle oximetry and rate of perceived exertion were collected. RESULTS: Both…small-sided games formats induced changes in sprint performance (before-after comparison), in the rate of perceived exertion, heart rate-related variables and time-motion parameters (p < 0.05). In a comparison between small-sided games formats, lower values of oxygen saturation, heart rate, rate of perceived exertion and time-motion parameters (p < 0.05) were reported during small-sided games with wildcard players in both working and recovery periods. CONCLUSIONS: The inclusion of wildcard players during small-sided games cause a reduction in perceptual, physiological demands and time-motion parameters when compared to control condition.
Abstract: BACKGROUND: Cluster Training (CL) is an alternative to traditional training where intra-set breaks are incorporated. Positive effects have been reported on sports performance. However, there is little research on body composition in trained subjects. OBJECTIVE: The aim of this study was to investigate the effects of three cluster training (CL) protocols comprised of different intra-set rest (RIntra) and blocks of repetitions (BK) on strength, power and body composition in individuals maintaining a high protein diet. METHODS: Twenty-nine resistance-trained male participants were randomized to RIntra 20 s and BK 3 RM (n =…8, CL1), RIntra 40 s and BK 3 RM (n = 7, CL2), RIntra 20 s and BK 6 RM (n = 7, CL3), and control group (n = 7, CG). All participants performed two sessions per week of lower-limb resistance training for 8 weeks. RESULTS: There were significant changes in FFM in CL1 (0.9 ± 0.5 kg, P = 0.001, ES = 0.17), CL2 (0.6 ± 0.5 kg, P = 0.010, ES = 0.14) and CL3 (0.6 ± 0.4 kg, P = 0.011, ES = 0.14) but not in CG (0.4 ± 1.1 kg, P = 0.323, ES = 0.13). Likewise, significant increases were found in the cluster groups (CL1, 14.5 ± 12.3, P = 0.012, ES = 0.80; CL2, 10.1 ± 4.3, P = 0.001, ES = 0.60; CL3, 9.5 ± 4.9, P = 0.002, ES = 0.45) but not in CG (9.0 ± 9.0, P = 0.057, ES = 0.55). There were no significant changes for any group in CMJ. CONCLUSIONS: We conclude that a RIntra of ∼ 20 s in CL protocols with 3 RM blocks in multi-joint exercises of the lower-limb is sufficient to elicit significant training adaptations; no additional benefits were obtained using longer rest intervals.
Abstract: BACKGROUND: Sit-to-stand test is very often used as measure of lower limb strength in elderly adults. However, the recent findings indicate that performance in this test is also influenced by other factors. OBJECTIVE: To investigate the association between anthropometric, lower limb strength, and balance variables with the 5-repetition sit-to-stand test (5RSTST) in elderly women. METHODS: Forty physically active elderly women ⩾ 60 years underwent the 5RSTST and anthropometric, balance, and lower limb strength assessment. Anthropometric measurements included height and weight. Balance was quantified in the bipedal upright stance on the…basis of the centre of pressure sway in the anteroposterior (CoP AP ) and mediolateral (CoP ML ) direction. Bilateral concentric strength of the ankle plantarflexors and dorsiflexors, knee flexors and extensors, and hip extensors was measured. RESULTS: The time to complete the 5RSTST was significantly but mildly associated with height (r = 0.356, p = 0.024), ankle dorsiflexor strength (r = - 0.413, p = 0.017), knee flexor strength (r = - 0377, p = 0.030), knee extensor strength (r = - 0.411, p = 0.017), hip flexor strength (r = - 0.359, p = 0.040) on dominant limb, and balance in both directions (AP, r = 0.651, p < 0.001; ML, r = 0.647, p < 0.001). Balance control in AP direction and knee extensor strength on dominant limb were the only factors that contributed independently to 5RSTST, accounting for 55% of the variance. Balance control in AP direction alone explained 41% of the variance in 5RSTST. CONCLUSIONS: Balance control in AP seems to be the most important factor explaining the 5RSTST performance.
Abstract: BACKGROUND: Cervical stabilization exercises and local vibration may improve proprioception and balance and prevent musculoskeletal problems. OBJECTIVE: To compare the effects of local vibration and cervical stabilization exercises on balance, cervical joint position sense, and muscle performance in healthy participants. METHODS: Forty-eight healthy male participants without neck pain were included. The participants were randomly divided into three groups: a home exercise program lasting eight weeks to the cervical stabilization group; 60 s of vibration to the neck muscles of the local vibration group and a control group. Balance, joint position sense, and muscle…performance were evaluated twice in all subjects, before and after the intervention. RESULTS: Joint position sense error values were decreased in both the local vibration and cervical stabilization groups. Balance was improved (p < 0.001) in the local vibration group while improvement in muscle performance parameters was only seen in the cervical stabilization group (p < 0.05). CONCLUSIONS: The methods used in the present study may be used for improving the proprioceptive and vestibular components of balance in individuals with musculoskeletal problems such as cervical disc herniation, cervical spondylosis, or neck pain. However, given the limitations, much more research is needed to firmly establish these recommendations.
Keywords: Proprioception, balance, vibration, stabilization exercise, joint position sense
Abstract: BACKGROUND: Life expectancy among older adults has dramatically increased and they are one of the fastest growing populations worldwide. Maintaining quality of life and the ability to live independently are often of greater importance than overall life expectancy. OBJECTIVE: To present reference values for tests of muscle function, and to study the relationship to a commonly used tool of generic health related quality of life (HRQL) in older Swedish adults. METHODS: The study consisted of 192 individuals (105 women) aged between 65 and 80. The tests included hand grip and isometric knee extension…strength measurements, the standing heel rise test and a 30 m walking test. Health-related quality of life (HRQOL) was evaluated using the SF-36. RESULTS: Reference values for the measured parameters are presented. There were high correlations (n = 192) between handgrip and leg extension strength (r = 0.72–0.75; p < 0.01). The walking test’s self-selected speed demonstrated the strongest correlation with the physical component summary of the SF-36 (r = 0.57; p < 0.01) and with maximal speed, moderate correlations were demonstrated with muscle strength (r = 0.43–0.56; p < 0.01) and the heel rise test (r = 0.45; p < 0.01). CONCLUSIONS: This study presents reference values for simple tests of muscle function which are relatively easy to perform, used in a Swedish clinical setting performing screening for older adults.
Keywords: Aging, hand grip strength, muscle strength, SF-36
Abstract: BACKGROUND: Knee osteoarthritis (OA) is common among older adults and associated with impaired knee strength. OBJECTIVE: Describe isokinetic testing procedures and clinimetric findings associated with the testing of knee strength in the presence of knee OA. METHODS: Relevant articles were identified by an electronic search of PubMed using the search string “isokinet * AND knee osteoarthritis.” RESULTS: One-hundred and twenty-nine relevant articles were found. The articles support the validity and reliability of isokinetic strength testing for patients with knee OA. The responsiveness to various therapeutic interventions…has been reported. CONCLUSIONS: Isokinetic dynamometry is a valid and reliable measure of muscle strength in knee OA.