Isokinetics and Exercise Science - Volume 28, issue 4
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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: 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: An increase in the compensatory action of the quadratus lumborum (QL) during side-lying hip abduction (SHA) can lead to lateral movement impairment of the pelvis. OBJECTIVE: To compare the effects of knee flexion (KF) and knee extension (KE) during SHA at abduction angles of 25 ∘ , 35 ∘ , and 45 ∘ on the activity and onset time of the gluteus medius (GM) and QL. METHODS: Thirty healthy men were recruited and randomly divided into two groups: those with SHA with…KF and those with SHA with KE. The subjects performed SHA at three angles of abduction in a random order. Surface electromyography was used to record the muscle activities of the GM and QL. RESULTS: The QL activity decreased significantly more in the KE group than in the KF group at each of the three angles of abduction during SHA. The GM/QL activity ratio increased significantly in the KE compared to the KF group. In addition, in the KE group, the onset of the GM activity was significantly earlier than that of the QL activity. On the other hand, in the KF group, the onset of the GM activity occurred later than that of the QL activity. CONCLUSIONS: These findings indicate that KE is more effective than KF in selectively activating the GM during SHA by reducing the QL activity and firing the GM earlier than the QL.
Keywords: Side-lying hip abduction, electromyographic activity, onset time, gluteus medius, quadratus lumborum
Abstract: BACKGROUND: Neuromuscular electrical stimulation (NMES) is a complementary tool for therapeutic exercise for muscle strengthening and may potentially enhance exercise performance. OBJECTIVE: To determine whether high-intensity interval training (HIIT) and continuous aerobic training (CA) coupled with NMES enhance the changes in the eccentric/concentric muscle contraction patterns of hamstring and quadriceps. METHODS: Forty-five healthy sedentary male participants performed cycling training 3 times per week for 8 weeks combined with/without NMES performed at a load equivalent to 65% and 120% of I VO 2max (intensity associated…with the achievement of maximal oxygen uptake). Anthropometrics, blood lactate measurements, I VO 2max , T Lim VO 2max (time-to-exhaustion) and isokinetic strength parameters were measured at baseline and post-training using a randomized controlled trial. RESULTS: The conventional hamstring-to-quadriceps-ratio (HQR: Hcon/Qcon) at 60 ∘ /s and the Dynamic Control Ratio (DCR: Hecc/Qcon) at 180 ∘ /s significantly increased both in the dominant (D) and non-dominant (ND) limb in the HIIT + NMES group (p < 0.05). There was a positive significant correlation between the individual changes in D HQR at 60 ∘ /s and I VO 2max (r = 0.94, p = 0.005) and the DCR at 180 ∘ /s and T Lim VO 2max (r = 0.90, p = 0.015), respectively. CONCLUSIONS: The increases in the eccentric muscle contraction and DCR following HIIT + NMES seem to improve fatigue tolerance, cause less fatigue and oxidative stress on the lower limb during pedaling at high intensities.
Keywords: Blood lactate concentration, conventional and functional H:Q ratio, isokinetic strength, time to exhaustion, maximum oxygen consumption
Abstract: BACKGROUND: Kicking is the major way to score in a Taekwondo competition, which makes athletes’ leg power a key quality. However, the characteristics of leg power are very complex and it is difficult to generate physical models to predict training performance. OBJECTIVE: To study training programmes of leg power for Taekwondo using data-driven techniques in correlation analyses and modelling. METHODS: An 8-week program for back squat training was performed using two devices, a Cormax training system and a conventional barbell. Data analysis was conducted to identify the factors affecting the explosive power training.…Finally, a data-driven modelling paradigm employing fuzzy rule-based systems was developed to predict the training performance. RESULTS: The Cormax system performed better in improving athletes’ maximum power and velocity. Maximum leg power was best correlated with athletes’ height. The developed predictive models showed good accuracy despite possession of limited training data. CONCLUSIONS: This study demonstrated some new training devices which could greatly improve power training. Moreover, a state-of-the-art modelling strategy was able to construct accurate models for training and exercise performance. The predictive models will likely enhance the anticipation of training outcome in advance which may assist in formulating and improving the training programmes.
Keywords: Taekwondo, leg power, training, weighted squat, data-driven modelling, fuzzy rule-based system
Abstract: BACKGROUND: Whole-body electromyostimulation (WB-EMS) is a new tendency in training used to complement conventional training. OBJECTIVE: The aim was to analyze the effects of training with WB-EMS on body composition, strength and balance in middle-aged women. METHODS: Twenty-eight women were randomly assigned to two groups: the WB-EMS group (age = 48.1 ± 4.3 years) or the control group (CG) (age = 51.1 ± 5.4 years). All participants continued their training of 2 days⋅ week - 1…and 60 min⋅ day - 1 of endurance-dynamic strength exercises and additionally did 20 minutes more of dynamic strength exercises one day⋅ week - 1 : the WB-EMS group did the additional training with WB-EMS and the CG did the same training but without WB-EMS. Body composition, muscle isokinetic strength of the knee flexors/extensors and postural stability were measured before and after 8 weeks of training. RESULTS: After the training program, the WB-EMS group showed lower values for the waist circumference (83.00 ± 7.37 vs. 78.50 ± 7.30 cm; p < 0.01), hip circumference (104.80 ± 8.61 vs. 101.00 ± 6.78 cm; p < 0.05) and total fat mass (37.04 ± 6.08 vs. 36.26 ± 5.78%; p < 0.05). In balance stability the WB-EMS group reduced their Fall Risk Index (1.70 ± 0.51 vs. 1.30 ± 0.38 AU; p < 0.01) and deviation (1.50 ± 0.43 vs. 1.03 ± 0.74 AU; p < 0.01) after training and showed lower values in the Fall Risk Index (p = 0.007) and deviation (p = 0.024). CONCLUSIONS: The WB-EMS training program helps reduce the risk of falling and improves body composition variables and balance results in middle-aged physically active women.
Keywords: Exercise, electromyostimulation, WB-EMS, body composition, balance, strength
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: The maintenance of maximal aerobic speed (MAS) until exhaustion is an important parameter for the evaluation of sports performance and prescription and planning of training. OBJECTIVE: To validate a 6-minute race test (6MRT) as a predictor of MAS in university endurance athletes. METHODS: Twenty two university endurance athletes (12 males and 10 females) were part of the study. The design was pre-experimental. The primary variables were the time of maintenance of the MAS on the field through a Time Limit Test (Tlim test), and the VO 2 max…(laboratory and field). The statistical analysis of the time and ventilatory variables was carried out using descriptive statistics; the comparison between males and females for all variables was carried out through a t-Student test for independent samples (p < 0.05). RESULTS: The performance in the Tlim test was 356.4 ± 52.9 and 327.0 ± 120.2 s in males and females, respectively. CONCLUSION: Based on the time of maintenance of the MAS (Tlim test), the 6MRT is a valid test to determine the MAS in university endurance male athletes. However, the MAS in university endurance female athletes must be evaluated with a shorter test (between 5 and 5.30 minutes long).
Keywords: Maximal aerobic speed, maximal oxygen uptake, time limit test, university endurance athletes
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: 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: Active interventions for pes planus, including short-foot exercises (SF) and toe-spread-out exercises (TSO), aim to continuously support the medial longitudinal arch (MLA) by activating the abductor hallucis (AbdH) muscle. However, compensatory movements, such as ankle supination and/or plantar flexion, often occur during these exercises. OBJECTIVE: To examine the effects of a novel exercise, i.e., the toe-tap (TT) exercise on AbdH activity and MLA angle. METHODS: A total of 16 participants with pes planus participated in this study. Participants performed SF, TSO, and TT exercises. Electromyographic activity of the AbdH and MLA angle…during three AbdH contraction exercises were recorded using surface EMG system and digital image analysis program, respectively. The differences in outcome measures among the three exercises were analyzed using one-way repeated-measures analysis of variance. RESULTS: The EMG activity of the AbdH was significantly greater during the TT exercise compared to the SF and TSO exercises. The MLA angle was significantly smaller during the TT exercise compared with the SF and TSO exercises. CONCLUSIONS: These findings suggest that the TT exercise could be effective in activating the AbdH and increasing height of the MLA, as part of a sports rehabilitation program for individuals with pes planus.
Keywords: Abductor hallucis, medial longitudinal arch, pes planus