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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: Exercises that stretch the gastrocnemius (GCM) lead to greater ankle dorsiflexion (DF). GCM stretching combined with talar self-stabilisation has been reported to increase ankle DF range of motion (ROM). However, excessive subtalar and midtarsal pronation during GCM stretching may compensate for reduced ankle DF. Thus, this study examined the combined immediate effect of stretching GCM and stabilising talus and subtalar supination on limited ankle DF. OBJECTIVE: This study aimed to investigate the immediate effect of GCM stretching alone, GCM stretching with talar self-stabilisation and GCM stretching with talar self-stabilisation and subtalar supination on ankle kinematics…in subjects with limited ankle DF. METHODS: Fifteen subjects with limited ankle DF were recruited. The subjects performed the three abovementioned methods. RESULTS: GCM stretching with talar self-stabilisation and subtalar supination significantly increased open-chain and closed-ankle DF ROM compared with GCM stretching alone. Moreover, GCM stretching combined with talar self-stabilisation and subtalar supination significantly increased open-chain ankle DF ROM with knee straight compared with pre-intervention (P < 0.017). CONCLUSIONS: The preferred method to increase ankle DF ROM is GCM stretching combined with talar self-stabilisation and subtalar supination.
Abstract: BACKGROUND: While extreme changes in body position (e.g., standing vs. sitting) have been shown to affect knee extensor strength, little is known regarding how less extreme changes in body position affect knee extensor strength and activation. OBJECTIVE: This study evaluated the effect of four seated positions on the maximum voluntary isometric contraction (MVIC) and electrically-evoked isometric strengths of the knee extensors. METHODS: Forty healthy subjects participated. MVIC strength, electrically-evoked strength, and voluntary activation of the quadriceps muscles were measured under four seated positions: 1) 22.5–25 ∘ forward tilt, 2)…0 ∘ tilt, 3) 22.5–25 ∘ backward tilt, and 4) 45–50 ∘ backward tilt. The effect of seated position on each dependent variable was assessed using a one-way repeated measures ANOVA with linear contrasts. RESULTS: MVIC and electrically-evoked strengths increased (P ⩽ 0.037) by 5–11% as the body was moved from the 22.5–25 ∘ forward-tilted to 45–50 ∘ backward-tilted position. However, voluntary muscle activation and EMG amplitudes of the knee extensors during MVIC did not change. CONCLUSIONS: Knee extensor MVIC and electrically-evoked strengths were modestly enhanced as the body was tilted backwards. The use of a semi-reclined position may assist in obtaining a more forceful contraction of the knee extensors, thereby potentially resulting in better strength training outcomes.
Abstract: BACKGROUND: The majority of common agility tests include pre-planned change of direction (COD) maneuvers which require muscular coordination. However, muscular coordination in terms of organization of co-activated antagonistic muscle pairs in COD maneuvers have not been studied. OBJECTIVE: To evaluate muscle coordination by analyzing co-contraction at knee and ankle during three agility tests; ii) to investigate the relationships between muscle coordination and test completion time. METHOD: Thirteen healthy young male subjects (22.1 ± 1.9 years) participated in the study. Surface EMG and acceleration signals were used to calculate co-contraction index…(CCI) for selected antagonistic muscle pairs of ankle and knee joints during COD maneuvers in agility tests. RESULTS: The findings indicated that concurrent activation costs a delay to complete the test faster. CCI was higher at right ankle and left knee and showed an increasing trend with advancing the phase when the test requires multiple CODs. CONCLUSIONS: Minimizing co-contraction would result in faster movement, however, there might be a trade-off between joint stiffness and test performance depending on changes in neuromuscular factors such as altered motor control strategies due to strength imbalances or occurrence of fatigue.
Abstract: BACKGROUND: The introduction of high-intensity functional training (HIFT) in sport gave rise to the exploration of determinants of success in sport. OBJECTIVE: To analyze whether inter-limb performance asymmetry (ILPA) between limbs is related to reduction in physical performance in amateur HIFT athletes. METHODS: Twenty-four HIFT amateur athletes, 11 women and 13 men, participated in the study. All volunteers performed three different jump tests: the squat jump (SJ), the countermovement jump (CMJ), performed unilaterally and bilaterally, and the 20-m sprint test. RESULTS: An overall ILPA of 9.5% in women and 9.3%…men was not associated with any of the outcome measures. There were no significant differences in both genders between asymmetry, sprint, lower limbs’ muscle power (LLMP), SJ, CMJ and stretch-shortening cycle (SSC) (p > 0.05). CONCLUSIONS: ILPA in CMJ does not seem to affect the performance of amateur athletes of HIFT. Thus, when the target is to maximise the performance, in the training programme, coaches should prioritise tasks that increase vertical jump capacity at the detriment of the unilateral jump.
Keywords: Inter-limb differences, jumping, performance reduction, sprint, muscle power
Abstract: BACKGROUND: The ergogenic effect of ischemic preconditioning (IPC) has been widely approved, but the mechanisms underlying the beneficial effects are still not fully clarified. OBJECTIVE: The aim of this study was to examine the effects of IPC on human isokinetic muscular function and hemodynamics during exercise. METHODS: In a counterbalanced, crossover study, 14 healthy non-athletic males (26.0 ± 3.5 years) performed isokinetic muscle strength and endurance tests of the dominant leg on an isokinetic dynamometer, preceded by either IPC on bilateral thighs (3 × 5-min compression/5-min reperfusion…cycles at 50 mmHg greater than the participant’s systolic blood pressure) or SHAM (10 mmHg) intervention. Participants underwent strength testing by performing three maximum isokinetic knee extensions and flexions at the angular velocities of 30, 150 and 270 ∘ /s. An endurance test was also conducted over 30 repetitions at 180 ∘ /s. Hemodynamics of the vastus lateralis muscle were monitored before and after the interventions and during exercise tests by near-infrared spectrometer (NIRS). RESULTS: Resting total hemoglobin significantly increased after IPC (p = 0.048, d = 0.15). During the endurance testing, the oxygen uptake was significantly improved after IPC as shown by the change of oxygenated hemoglobin, deoxygenated hemoglobin, and oxygen saturation, at small to moderate effect size. However, both muscular strength and endurance were found unchanged. CONCLUSION: IPC improves the local oxygenation status without altering maximal muscle strength and endurance in young non-athletic males.
Abstract: BACKGROUND: No studies so far have investigated the effectiveness of the short-term intervention on the capacity of the ISP during throwing motion in baseball player with throwing disorder. OBJECTIVE: To investigate the effectiveness of short-term intervention on ISP during throwing motion and of physical examination in baseball player with throwing disorder. METHODS: Twenty-seven male baseball players with throwing disorder were hospitalized for 1 week and received physical therapy for 1 hour a day. In the pre- and post-hospitalized period, participants were evaluated using physical examinations (Hara test) and ISP and posterior deltoid muscle activity during…throwing motion. RESULTS: The ISP during the late-cocking phase and follow-through phase at the time of hospital discharge were significantly greater than that at the hospital admission (P < 0.05). The effect sizes revealed large effects for follow through phase (r = - 0.60). The positive rate of the Hara test decreased significantly in all examination items except scapula-spine distance, subacromial impingement test, and hyper-external rotation test. CONCLUSIONS: The ISP in throwing motion is important to the stability of the glenohumeral joint during follow-through phase. Our results indicated that the improvements in the physical examination reflected favorably on the ISP during the throwing motion.
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.