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: BACKGROUND: Rate of torque development (RTD) could serve as a useful index for the readiness and fatigue of soccer players. OBJECTIVE: The identification of RTDs time-course changes after a Loughborough Intermittent Shuttle Test (LIST), the effect of bovine colostrum (BC) supplementation on RTD changes, and to explore the relationships between RTD and selected muscle damage blood markers. METHODS: Twenty-two soccer players completed a pre-supplementation LIST (LIST1). Subsequently, subjects were randomly divided into whey protein (WP, N = 8) and bovine colostrum groups (BC, N =…10) receiving 3.2 g of WP or BC for 6 weeks. Participants repeated LIST (LIST2) after supplementation. Hematological markers, CK, CRP, IL-6 and RTD at 20–250 ms were determined pre- and 2–72 h post-LISTs. RESULTS: RTD declined after LIST1 (- 48.1 ± 22.1%–- 10.7 ± 8.2%). Late RTDs showed lower reductions compared to early RTDs’. Supplementation of WP or BC attenuated the decline of late RTDs until 72 hours post LIST (p < 0.05; η 2 : 0.236–0.287). BC group achieved lower reductions of RTDs after LIST2 compared to WP group. The percent changes of RTDs were correlated with changes of biochemical markers post-LIST. CONCLUSIONS: LIST induces a significant decline in RTD of soccer players. BC could be a promising supplement alleviating the impairment of RTD after a soccer game.
Keywords: Rate of torque development, rate of force development, soccer, bovine colostrum, recovery, muscle damage, inflammation
Abstract: BACKGROUND: Strengthening exercises help improve physical function and muscle strength in knee osteoarthritis (OA). However, optimal exercise programmes for treating knee OA remain unclear. OBJECTIVE : To compare efficacy of isometric exercises performed at different angles and isokinetic exercises in patients with knee OA. METHODS: Patients were randomly divided into two groups. For four weeks, Group I (n = 15) and II (n = 17) patients with grade 2–4 performed isokinetic and isometric exercises at several different angles, respectively. Flexor and extensor knee muscle…strengths were measured. Pain and physical function were assessed using VAS, WOMAC, the Lequesne Index and SF-36. All parameters were recorded at three time points: baseline (T0), after treatment (T1) and at 10-week follow-up (T2). RESULTS: VAS on movement, WOMAC, Leuqesne and SF-36 physical scores improved from T0 to T2 within each group, but Grade 3 and Grade 4 patients in the Group I showed better results compared with Group II at T2. Isokinetic exercise yielded higher extensor PM values than its isometric counterpart at T2 (P < 0.05) at 180 ∘ /s for Grade 2 and Grade 3 patients. CONCLUSIONS: Both isokinetic and isometric exercises were effective in the treatment of knee OA of all grades in terms of pain reduction and functional improvements. However, isokinetic exercise produced longer lasting effects than isometric exercise.
Abstract: BACKGROUND: Adolescence is characterised by a rapid and erratic growth period many factors completely change in growth period up to 20 years of age, with a very slight alteration during the later years of life. Bioelectric impedance analyzers (BIA) are used in estimating the total and segmental body composition compartments. OBJECTIVE: To determine the validity of different BIAs for young male athletes. METHODS: Sixty-one young male athletes (basketball, football, handball, swimming, and skiing) participated in the study. The validity of Tanita 401A (TANITA), Jawon Segmental Body Composition Analysers model AVIS 333 Plus (AVIS), and…Biodynamics Model 310e (BIODYNAMICS) was tested by Bland & Altman analysis and heteroscedasticity, providing the gold standard criterion method, hydrostatic weighing (HW) for body density (D b ), body fat percentage (%BF), and lean body mass (LBM). RESULTS: BIA models used for predicting body composition, except for %BF of TANITA, are valid and in accord with HW for young male athletes. TANITA had significantly lower %BF (5.75 ± 2.95%) and higher LBM (62.12 ± 7.53 kg), compared to HW (10.79 ± 4.17 %BF and 58.80 ± 7.38 kg LBM). Percent BF of BIODYNAMICS and AVIS results were significantly higher (2.04% and 3.3% respectively) than %BF of HW. CONCLUSION: Prediction of body composition compartments of young male athletes using BIA models is valid except for %BF by TANITA. LBM values of HW and BIA models can be used interchangeably. However, these BIA softwares do not have specific options concerning athletic status for the growing age and sex group to clarify population specificity in adolescent male athletes. Therefore, using the same BIA model is recommendable in following up training regimen and nutritional status, in order to avoid underestimating or overestimating the body composition compartments.
Keywords: Validity, bioelectric impedance analysis, body composition, hydrostatic weighing, young male athletes
Abstract: BACKGROUND: Blood flow restriction (BFR) exercise benefits muscle performance. However, there is limited research on vascular dysfunction, particularly using involuntary muscle contraction modality plus BFR. OBJECTIVE: To investigate the acute and accumulative effects of whole body vibration (WBV) with BFR on vascular dysfunction, as evaluated by von Willebrand factor (vWF) levels. METHODS: Physically inactive men were randomly assigned to the WBV + BFR group (n = 8) and the WBV group (n = 8). Participants in the WBV group were…subjected to 10 sets of internment WBV exercise 20 min/day, 3 days/week for 8 weeks. Participants in the WBV + BFR group received the same WBV treatment, but the proximal portion of the thighs was compressed by inflatable cuffs. RESULTS: The increase in vWF levels in the acute WBV + BFR group was significantly higher (P < 0.05) by 17.2% than that in the WBV group. However, vWF levels exhibited equal decrements in the two groups after training (P > 0.05). CONCLUSIONS : WBV + BFR may acutely cause vascular dysfunction potential to a greater extent than WBV alone. However, regular WBV and WBV + BFR training may produce an equally beneficial effect on vascular function in a previously untrained population.
Abstract: BACKGROUND: The circadian rhythm (CR) is a 24-hour cyclic period that influences a wide array of physiological systems and performance sports. However, its specific effect on drop jump (DJ) scores have not been studied. OBJECTIVE: To investigate the effect of circadian rhythm on DJ performances. METHODS: Thirty-three healthy university students (men, n = 16, age: 23.47 ± 2.9 years; fewomen, n = 17, age: 22.25 ± 2.27 years) participated in this study. Subjects were tested twice, over two…separate days, once in the morning and once in the evening. Subjects started from a drop height of 20 cm and continued until the height where the reactive strength index (RSI) started to decrease. This height was recorded as the optimal drop height (ODH). Ground contact time (GCT) and jump height were also recorded. RESULTS: The ODH values were similar between testing sessions for both genders (p > 0.05). A significant increase in jump height during the evening session was observed in men (p = 0.005, d = 0.80). The RSI values increased significantly in men (p = 0.006, η 2 = 0.77) while GCT was similar in both genders (p > 0.05). CONCLUSION: In men, the optimal time of day for DJ explosive training is the evening. Women may benefit from this type of training both during morning and evening sessions.
Keywords: Circadian rhythm, drop jump, reactive strength index, optimal drop height, jump height, ground contact time
Abstract: BACKGROUND: The abdominal draw-in maneuver (ADIM) has been suggested to increase trunk stabilizing muscle activity; however, no study has identified the effects of the ADIM on trunk muscles and trunk movements during lifting and lowering (L & L) tasks. OBJECTIVE: We examined the effects of the ADIM on transversus abdominis (TrA) thickness during standing, the activity of the TrA, internal oblique (IO) and multifidus (MF), and the kinematics of the lumbo-pelvic-hip complex during L & L tasks. METHODS: Fifteen male participants practiced expirations without and with the ADIM using ultrasound biofeedback. After…training for each condition, the participants performed expirations with and without the ADIM in the standing position and during L & L tasks. TrA thickness during the standing position and muscular activities (EMG) of the bilateral TrA/IO and MF, and the peak angle of the lumbo-pelvic-hip complex in the sagittal plane during L & L tasks were measured. RESULTS: TrA thickness during standing was increased with expiration with ADIM compared to that without the ADIM (p < 0.05). When performing expiration with the ADIM, increased activity of the TrA/IO and MF was observed by EMG, as well as peak pelvic anterior tilt and hip flexion with decreased peak lumbar flexion during L & L tasks (p < 0.05). CONCLUSIONS: The ADIM could be an effective strategy to improve trunk stability and reduce lumbar flexion during L & L tasks.
Keywords: Abdominal draw-in maneuver, electromyography, manual material handling, trunk stability
Abstract: BACKGROUND: In countries where water polo is a minority sport, coaches often recruit young players to senior teams. OBJECTIVE: To explore whether young water polo players are ready to train and play with older players from a physical and strength perspective. METHODS: Forty-four adolescent and senior water polo players (20 women and 24 men) were evaluated on full anthropometry, absolute and relative isokinetic muscle strength of shoulder internal and external rotator muscles (60 and 240 ∘ /s) and hand grip strength. RESULTS: The strength of the internal…rotators was significantly greater than that of the external rotators in both sexes and age groups. Senior male players had significantly higher values for variables related to body size and absolute strength in these muscle groups compared to their adolescent counterparts but these differences were not observed among women. CONCLUSIONS: Adolescent female players but not male players may be physically prepared to compete and train with senior teams.
Keywords: Team sport, body size, adolescence, strength training, performance
Abstract: BACKGROUND: In recent years, power assist suit has been applied in nursing and rehabilitation scenarios. The external assistive force might disturb the user’s motor control system during the process of assisted training using power assist suit, thus affect the progress of rehabilitation. With the consideration of the non-negligible physiological differences between upper limbs, this study focused on the physiological responses of the two arms against the external assistive force. OBJECTIVE: To investigate and contrast the impact of assistive force on dominant and non-dominant arms during unilateral isometric elbow flexion. METHODS: Participants were instructed…to adjust force exertion to a target value based on the visual feedback. Task performances including muscle activity of agonist and antagonist muscles, force steadiness and rated perceived exertion were evaluated at multiple workload and assistive load conditions. RESULTS: No significant differences in muscle activity of agonist and antagonist muscles between the two arms. In contrast, the dominant arm showed a higher assist efficiency at a low assistive level, whereas the non-dominant arm had a lower level of force fluctuation during a unilateral force matching task. CONCLUSIONS: Both arms could utilize the assistive force to reduce muscle activity. However, the two arms showed different abilities in response to external assistive force. This indicates distinct motor control strategies for each arm and implicates the necessity of side-individualized rehabilitative approach for achieving a better training effect.
Abstract: BACKGROUND: Warm up exercises are common practice before training and competition in almost every sport. Although, swimming is a popular sport throughout the world, studies on the effects of warm-up are scarce. OBJECTIVE: The purpose of this study is to compare the effects of different stretching warm-up and exercise protocols on swim performance. METHODS: Fourteen sub-elite college women swimmers volunteered to participate in the study. The four stretching and warm-up protocols they followed were; (I) without stretching (WS); (II) static stretch (SS); (III) in-water (IW); and (IV) dry land (DL). RESULTS: There…was a significant main effect for 50-meter front crawl (F = 70,453; p = 0.00) and breaststroke swimming performances (F = 145.504; p = 0.000). The best 50-meter front crawl and breaststroke performance detected immediately after IW was 28.1 and next, 39.9 seconds. Pairwise comparison indicated that the best 50-meter front crawl performance monitored after IW protocol was 28.0 ± 2.9 (p = 0.000) compared with that after WS – 29.8 ± 2.3 (p = 0.000) and after SS – 30.7 ± 2.2 (p = 0.000). CONCLUSIONS: Pre-event low-intensity IW warm-ups may be optimal for 50-meter front crawl and breaststroke swimming performance.
Keywords: Swimming, stretching, warm up, women, front crawl, breast stroke
Abstract: BACKGROUND: Extensive research has been conducted related to muscle fatigue, but little attention has been given to shoulder rotator muscles. Many different formulas have been used to calculate fatigue. Therefore, there is a need for establishing a reliable fatigue assessment protocol to further assess shoulder rotators using a suitable fatigue formula. OBJECTIVE: To study the reproducibility of two different isokinetic set-ups for assessing shoulder rotators fatigability properties and explore a possible clinical implication when different fatigue calculation formulas are used. METHODS: Forty sedentary subjects took part in this study. They were randomly assigned…to either the “45 ∘ group” or the “90 ∘ group”, where the upper limb was either abducted to an angle of 45 ∘ or 90 ∘ in the frontal plane, respectively. All participants completed two testing sessions, consisting of 30 maximal concentric contractions on dominant shoulder IR and ER muscles at 180 ∘ /s. Relative reproducibility, absolute reproducibility and fatigue indices were assessed. RESULTS: ER was different (p < 0.05) between trials (5%). Relative reproducibility was high for both muscles (ICC 0.97–0.99). Absolute reproducibility remained homogeneous with a SEM of 4–6% while the MDC varied between 11% and 16%. Fatigue formulas estimated no difference between trials (0–2%) for any muscle groups. CONCLUSIONS: Based on this study of reproducibility, both abduction set-ups may be used for assessing fatigue performance without indicating a superiority for either.