Isokinetics and Exercise Science - Volume 26, issue 3
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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: BACKGROUND: Endurance is an important factor in athletic performance and is affected by respiratory muscle fatigue. Recent studies indicate that warming up of respiratory muscles improves the respiratory muscle fatigue. OBJECTIVE: To investigate the effects of inspiratory muscle warm-up on aerobic performance during incremental exercise. METHOD: Maximal inspiratory (MIP) and expiratory (MEP) pressures were measured in 30 healthy male athletes, with (EX) and without (CON) inspiratory muscle warm-up. RESULTS: No significant changes in MIP and MEP values between baseline levels and the CON condition were observed while such were seen…with respect to EX and between the EX and CON conditions (p < 0.05). Aerobic performance measurements, including peak oxygen uptake (VO 2PEAK ), relative VO 2PEAK , oxygen uptake to workrate slope (Δ VO 2 /Δ WR), metabolic equivalent (MET), peak heart rate (HR PEAK ), peak minute ventilation (VE PEAK ), peak tidal volume (TV PEAK ), peak respiratory rate (RR PEAK ), peak carbondioxide output (VCO 2PEAK ) and respiratory exchange rate (RER) significantly differed by 18.84%, 19.51%, 9.53%, 15.54%, - 4.36%, 19.90%, 32.77%, - 6.10%, 23.29% and 7.34%, respectively, between subjects in the EX and CON conditions. CONCLUSION: These results show that inspiratory muscle warm-up improves aerobic performance byt further investigation is required to elucidate the exact mechanisms that stand behing these variations.
Abstract: OBJECTIVE: To examine the effects of fatigue on force reproduction during internal and external rotation of the shoulder using a single group repeated measure design. METHODS: Seventeen healthy male subjects who did not regularly compete in overhand sports and had no history of glenohumeral complaints took part in the study. Force reproduction was measured in the dominant shoulder. A target force had to be reproduced in three consecutive trials before and after a fatigue protocol. Maximal voluntary contraction was assessed to determine the target force. Measured data before and after fatigue were analyzed as well as…error scores to examine the effect of fatigue. RESULTS: Repeated-measures analysis of variance revealed a significant influence only in the testing direction. No difference was found with the target value before or after the fatiguing repetitions. The inter-trial intra-class correlation coefficient showed high reliability. CONCLUSIONS : Force reproduction towards external rotation is more accurate than for internal rotation.
Abstract: BACKGROUND: Core exercises include exercises to train muscles that control and stabilize the movements of the abdomen, waist, and hip. Thanks to these exercises, the control and balance of the body are increased. Exercises on unstable surfaces increase the level of muscle activity, and by using elastic resistance tools, one or more joints can be simultaneously and efficiently trained. OBJECTIVE: To compare core exercises with Theraband and Swiss Ball in terms of core stabilization and balance performance. METHOD: A total of 22 women who perform recreational sports between 25 and 46 years of…age participated in the study. The participants were separated into two groups: Swiss Ball (SBC, n = 11) and Theraband (TBC, n = 11). Both groups were subjected to core exercise programs for 6 weeks, 3 days a week, around 40 minutes per day. Prior to and after the 6-week exercises, body composition, core stabilization, Star Excursion Balance Test (SEBT), and Stork balance test scores were compared. RESULTS: No difference was found between groups in terms of pre-test values. While the weight and body mass index values decreased in all groups, the balance and core stabilization test scores increased significantly. With the exception of the SEBT, which has increased significantly in the TBC group, there were no differences between the groups in none of the scores. CONCLUSION: As both training methods lead to positive effect on the tested variables, the choice of the specific method should probably be decided based on individual preference and the training environment.
Keywords: Core stabilization, balance, Theraband, Swiss Ball, body composition
Abstract: BACKGROUND: There are controversies regarding the optimal number of trials and intervals during required for testing of maximal handgrip strength. OBJECTIVES: To verify the minimum optimal number of trials (two versus three consecutive trials) and inter-effort interval (15, 30, 45 and 60-s) during the measurement of maximal handgrip strength. METHODS: One hundred healthy subjects, 51 males and 49 females, were enrolled. During the measurement of maximal handgrip strength, two consecutive trials were hypothesized to be the minimum necessary. We compared the maximal handgrip strengths between two and three consecutive trials at four different intervals (15,…30, 45, and 60-s). RESULTS: Irrespective of hand dominance, maximal handgrip strength was best measured with three consecutive trials rather than two at each interval (all p < 0.05 except 15-s intervals with the dominant hand). The values at 60-s interval (dominant hands: 40.6 kgf, non-dominant hands: 36.7 kgf) were significantly higher than at other intervals (all p < 0.05). CONCLUSIONS: Three consecutive trials with a 60-s interval might be the minimum needed for optimal measurement of maximal handgrip strength.
Keywords: Hand grip, grip strength test, trial, interval
Abstract: BACKGROUND: Studies have shown that Running Anaerobic Sprint Test (RAST) is population specific. OBJECTIVE: To investigate the validity of RAST in assessing the anaerobic power of young soccer players. METHODS: Thirty-one volunteer young amateur soccer players underwent a standardized WAnT test and a RAST test in random order. Peak power (PP), average power (AP), minimum power (MP), fatigue index (FI), blood lactate (LA), heart rate (HR) and ratings of perceived exertion (RPE) were determined during the tests. RESULTS: No significant differences were found between RAST-PP and WAnT-PP. RAST-AP and RAST-FI…were significantly lower than that of WAnT whereas, RAST-MP was significantly higher than WAnT-MP. RAST-LA after was significantly lower than WAnT-LA after ; however, mean and peak RAST-HR were significantly higher than WAnT. RPE responses were found to be similar between the tests. PP, AP and MP from the two tests were significantly correlated. The standard errors of the estimates values for PP, AP and MP were ± 78.5 W, ± 44.4 W and ± 38.7 W, respectively. Peak and mean HRs from two tests were significantly correlated. No significant association was present between RAST-LA and RAST-RPE, and WAnT-LA and WAnT-RPE, respectively. CONCLUSIONS: Although recruiting different physiological and metabolic processes, RAST may be used in place of WAnT to assess the anaerobic characteristics of young soccer players.
Abstract: BACKGROUND: There have been conflicting findings regarding the relationship between ankle muscle fatigue and a fatiguing run due to different selections of running protocol. Bruce protocol is strongly established as a maximum graded exercise test for volitional fatigue. OBJECTIVE: To determine if volitional exhaustion utilizing the Bruce protocol would result in localized ankle plantarflexor (PF) and dorsiflexor (DF) fatigue. METHODS: Twenty-three healthy individuals participated. Participants ran on a treadmill until they reached volitional exhaustion during performance of the Bruce protocol. Before and after volitional exhaustion, participants performed 3 maximum voluntary isometric contractions for…both PF and DF with electromyography (EMG) assessing activation of the tibialis anterior, peroneus longus, and medial gastrocnemius muscles. RESULTS: Volitional exhaustion resulted in ankle PF fatigue (moment: p < 0.001), ankle DF fatigue (moment: p < 0.001), median frequency (p = 0.021) and mean amplitude (p < 0.001) of the tibialis anterior (TA). CONCLUSIONS: That the general fatigue induced by the Bruce protocol caused ankle PF and DF fatigue. Identifying and understanding the neuromuscular responses to volitional fatigue following running are helpful in not only improving the comfort and enjoyment of physical activities, but also in enhancing training and safety of injuries associated of these activities.
Keywords: Running, maximum graded exercise test, electromyography, moment, isokinetic dynamometer
Abstract: BACKGROUND: Despite the importance of knowledge regarding the effects of different warm-up strategies not much is known about these effects and specific strategies with respect to basketball players. OBJECTIVE: To analyze the effect of different warm-up strategies on two specific functional actions of basketball, countermovement jump and speed. METHODS: Nineteen male basketball players aged between 19 and 27 (23.7 ± 1.1 years) were recruited. Experimental sessions were conducted with a 24 h interval in-between. The athletes performed randomly the five warm-up conditions (aerobic + resistance training, aerobic…+ jumps, resistance training + jumps, jumps only, and control condition) followed by the physical tests (countermovement jump and a 20-m sprint). RESULTS: All warm-up conditions increased significantly the countermovement jump and sprint performance mainly for the jumps only condition for countermovement jump performance (p = 0.01) and resistance training + jumps for sprint performance (p = 0.01). CONCLUSION: Warm-up with jumps was the most effective method for increasing countermovement jump while resistance training + jumps was the best strategy to enhance 20 m speed performance.
Abstract: BACKGROUND: Validity may refer to the inter-workout similarity of data from novel hardware to a device deemed the “gold standard”. The degree of familiarization to novel hardware may impact subsequent validity outcomes produced from repeated workouts. OBJECTIVE: To compare physiological, performance and perceptual variables to squats done with a barbell to those done with an exoskeleton intended as hardware for manned space flights. METHODS: Subjects made four laboratory visits. They did two familiarization sessions on the exoskeleton, followed by two workouts in which the sequence of the exercise hardware examined was determined by…a coin flip. Per workout they did four repetitions each against four loads (23, 34, 45 and 57 kg) separated by 90-second rests. For the final two visits the same dependent variables were obtained before, during and after workouts. Z-scores identified outliers that were eliminated from further analyses. Dependent variables were compared with paired t-tests, Cohen’s d effect size, Bland-Altman plots and Pearson product moment correlation coefficients. RESULTS: Less than 1% of our data were outliers. Values for our dependent variables generally exhibited considerable inter-workout similarity. CONCLUSIONS: Exoskeleton findings were similar to those from a barbell and warrant continued inquiry, such as with microgravity simulation in human subjects.
Abstract: BACKGROUND: Cluster set plyometrics (CSP) promise greater muscular performance than traditional set plyometrics (TSP). OBJECTIVE: The purpose of this study was to compare the influence of TSP and CSP warm-ups via bounce drop jump (BDJ) on reactive strength index (RSI), leg stiffness (K leg ), ground contact time (CT), and jump height (JH). METHODS: Thirteen male rugby players (age, 20.92 ± 2.25 years; body mass, 82.88 ± 9.22 kg; rugby experience, 3.61 ± 3.04 years; training volume, 10.69 ± 3.75 h/week) were…recruited for this study from two rugby clubs competing in the Second League in Turkey. The players completed 3 different set configurations of equal jump volume 72 h apart in a randomized, balanced order. The sets configurations were TSP (2 × 10 jump with 90 s interval), CSP-1 (4 × 5 jump with 30 s interval), and CSP-2 (10 × 2 jump with 10 s interval). Pre and post values of RSI, K leg , CT, and JH on each session were determined via the Myotest Pro system. RESULTS: Statistically significant changes were not found between pre- and post-values of RSI, K leg , CT, and JH in each session, either positive or negative (p > 0.05), as well as among the three different set configurations in any of the outcome variables according to post-results (p > 0.05). These findings indicated that low-volume TSP and CSP bounce drop jump had no effect on RSI, K leg , CT, and JH in male rugby players. CONCLUSIONS: Set configurations, jump volume, and intensity applied in this study may be too low to change muscle-tendon complex (MTC) stiffness and produce a post-activation potentiation (PAP) effect. Further research, with larger samples, is needed to determine which set configurations, jump volume (> 20 jumps/session), and intensity (box height > 30 cm) are the best option for enhancement of RSI, K leg , CT, and JH.
Keywords: Cluster set, traditional set, bounce drop jump, reactive strength index, leg stiffness, rugby