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: Intrinsic foot muscle (IFM) dysfunction and poor foot arch are associated with various foot conditions. Toe flexor exercise (TFE) has been used to improve it; however, the immediate effects of TFE on each IFM and how it relates to changes in navicular bone height (NH) are unclear. OBJECTIVE: This study aimed to investigate acute muscle swelling in the IFM after TFE and the association between changes in NH and IFM size. METHODS: Fourteen adults participated in this study. NH and cross-sectional area (CSA) of the IFM were acquired pre and post- TFE.…The CSA of the IFM, including the abductor hallucis (AbH), flexor hallucis brevis, flexor digitorum brevis, and quadratus plantae, was acquired with ultrasonography. In the TFE, each participant completed five sets of eight repetitions with maximum strength. RESULTS: The NH and CSA of all IFM significantly increased significantly post-TFE (p < 0.01). Only the increase in AbH was moderately and positively correlated with the change in NH (r = 0.54, p < 0.01). CONCLUSION: This study suggests that the acute swelling of AbH after TFE is associated with an immediate increase in NH, supporting the important role of AbH in the formation of foot arch.
Keywords: Ultrasound, intrinsic foot muscles, navicular bone height, toe flexor exercise, acute muscle swelling
Abstract: BACKGROUND: The knee is one of the most common injuries in sports. However, the incidence of knee injuries can be decreased by enhancing balance and neuromuscular control. OBJECTIVE: The aim of this systematic review and meta-analysis was to investigate how injury prevention programs (IPPs) that include balance training influence knee injury rates in athletes. METHODS: Data were obtained from different databases (1985–2021). Only randomised controlled trials that used IPPs that include balance training, were considered. Two investigators extracted data from the qualifying documents. The critical outcome data elements derived from the included studies…were the number of ACL/knee injuries, ACL/knee injury rates, exposure hours, compliance rate, and follow-up duration. RESULTS: Compared to the control groups, those who participated in the IPP had a 54% lower risk of knee injuries per 1000 hours of exposure (IRR 0.457 (95% CI 0.346–0.603), P = 0.001) and a 60% lower risk of ACL injuries per 1000 hours of exposure (IRR 0.401 (95% CI 0.215–0.750), P = 0.004). CONCLUSIONS: IPPs that include balance training may reduce the risk of knee injuries.
Abstract: BACKGROUND: Passive heating has attracted attention as a potentially promising recovery modality in sports. However, investigations of passive heating have yielded only inconsistent results for exercise performance. OBJECTIVE: To investigate the acute effects of local passive heating administered between repeated bouts of isokinetic exercise. METHODS: The experiment was a randomized crossover study. There was a total of three visits including a familiarization visit. During the remaining two visits, eleven healthy men performed three bouts of nine sets of isokinetic knee extensions using their dominant single-leg (30 repetitions/set, 180 ∘ /sec). A…15 min recovery, during which a local passive heating pad at control (CON) or heating (HT) was applied to the rectus femoris, was afforded after the 3rd and 6th sets (Recovery 1 and 2). Isokinetic exercise performance, as assessed by peak torque, total work, and average power was analyzed using two-way repeated-measures ANOVA. RESULTS: Following Recovery 1 and 2, isokinetic exercise performance, as assessed by peak torque, total work, and average power was reduced in Set 4 (p < 0.001, p < 0.001, p = 0.080) and Set 7 (p < 0.001, p < 0.001, p = 0.009) in the HT group relative to the CON group. Electromyography analysis revealed that signal amplitude was lower in the HT group in Set 4 (p < 0.001) subsequent to Recovery 1, and that firing frequency was higher in Set 7 (p = 0.002) in the HT group after Recovery 2. Furthermore, EMG time-frequency maps from one representative participant showed that following Recovery 1 and 2 peak energy decreased during the first five repetitions in Set 4 and 7. CONCLUSIONS: Local passive heating administered during recovery decreased subsequent performance of isokinetic knee extensors, muscle activation ability and increased firing frequency maintaining force output. Therefore, local passive heating is not an appropriate acute recovery strategy for isokinetic exercises.
Abstract: BACKGROUND: Moderate-intensity interval training (MIIT) may be a viable exercise format for improving body composition, aerobic fitness, and health-related variables. OBJECTIVES: This randomized trial aimed to analyze the effect of MIIT or high-intensity interval training (HIIT) on aerobic fitness, body composition variables, and resting metabolic rate (RMR) in women with overweight or obesity. METHODS: 31 sedentary adult women with overweight or obesity performed 7 weeks × 3 weekly sessions of either HIIT or MIIT. Physical and physiological tests were applied before and after training. RESULTS: In…both analyses (intention-to-treat and by adherence to the training), aerobic fitness showed a time effect (p = 0.041 and p = 0.015), but without differences between groups (p > 0.05). No group (HIIT vs. MIIT), time (pre vs. post), or interaction effects (group vs. time) were found for RMR, body composition markers (fat mass, body fat percentage, lean mass), or body mass index – BMI (p > 0.05). In addition, MIIT induced a relatively high drop-out rate. CONCLUSIONS: This study suggested that the short-term (7-weeks) interval exercise training was effective for increasing aerobic fitness, and moderate-intensity intervals were as effective as high-intensity intervals. However, neither training format was effective for changing RMR, body composition variables, or BMI of women with overweight or obesity. Clinical trial ID: RBR-9jd7b7.
Abstract: BACKGROUND: Those undergoing pelvic floor muscle training (PFMT) often experience difficulty in perception; therefore, an easier PFMT method should be devised. OBJECTIVE: To determine the effectiveness of combining PFMT with either vibration stimulation or visual feedback provided by a branded cushion (not a prototype) in increasing PFM muscle activity. Since PFM does not involve large joint movements, muscle activity was a suitable indicator. METHODS: Twenty healthy adults were included in this study. All participants performed PFMT under three conditions using a branded cushion: vibration stimulation, visual feedback, and a control. All three conditions…were provided separately. PFM activity of the midline of the perineum at two points was recorded as the root mean square measured using PFM electromyography, measured twice for each condition. Muscle activity ratio was obtained by calculating maximum voluntary contraction of PFM in pre- and post-PFMT conditions. RESULTS: PFM activity and muscle activity ratio were both significantly higher following PFMT under vibration stimulation and visual feedback conditions (p < 0.01, p < 0.01, respectively). CONCLUSIONS: PFMT accompanied by vibration stimulation or visual feedback could immediately raise PFM muscle activity. We believe this study contributes to improving PFMT efficiency by suggesting more suitable PFMT methods.
Abstract: BACKGROUND: An advantage that deadlift (DL) has over back squat (BSQ) is that the latter requires additional equipment (i.e., squat rack). Accordingly, if DL can lead to positive effects on jumping, acceleration, and change of direction, DL could present as a more practical training exercise than that of BSQ. OBJECTIVE: This study aimed to compare the effects of DL and BSQ on jumping, acceleration, and change of direction. METHODS: Twenty-three men (12 in the DL group [age: 20.3 ± 1.4 years old, height: 169.6 ± 6.7 cm, body weight:…65.7 ± 11.2 kg] and 11 in the BSQ group [age: 20.2 ± 1.9 years old, height: 171.5 ± 4.8 cm, body weight: 70.1 ± 6.8 kg]) participated in this study. The participants performed five repetitions maximum (RM) of DL and BSQ, and the isokinetic strength of hip joint extension, muscle thickness of the gluteus maximus and hamstrings, countermovement jump (CMJ) height, 10 m sprint time, and T-test results were measured. The 1RM was estimated using the 5RM and normalized to body weight (BW). Both groups performed supervised DL and BSQ training for eight sessions. RESULTS: There were significant improvements on 1RM DL/BW (p < 0.01), 1RM BSQ/BW (p < 0.01), and 10 m sprint (p < 0.01) in the two groups. The effect sizes ( d ) of the DL and BSQ groups were 2.01 and 1.04 for 1RM DL/BW, 1.08 and 2.08 for 1RM BSQ/BW, 0.35 and 0.11 for CMJ height, and - 0.94 and - 0.54 for 10 m sprint, respectively. CONCLUSIONS: DL training might improve jumping and acceleration compared to those of BSQ training.
Keywords: Strength training, maximum strength, deadlift, back squat
Abstract: BACKGROUND: Hamstring shortening altered joint reaction forces during activities of daily living (ADL), causing knee pain. Moreover, weak quadriceps may negatively distribute the compressive and shear forces at the knee joint. PURPOSE: The study examined the effect of adding hamstring stretching to quadriceps strengthening exercises on joint space narrowing (JSN), medial joint space width (mJSW), and physical abilities in patients with knee osteoarthritis (KOA). METHODS: A total of 42 osteoarthritis patients, aged from 50 to 65 years, were randomized and assigned into 2 groups: the study and the control groups. Quadriceps strengthening exercises…were given to both groups, while static hamstring stretching was applied to only the study group. Patients of both groups were screened with a weight-bearing x-ray beam to investigate the JSN, mJSW, and functional abilities measured in the WOMAC scale. The Outcomes were evaluated at the baseline and immediately after 6 weeks of treatment. RESULTS: The mJSW improved in the study group (p < 0.001) compared to the control group (p = 0.07). The OARSI JSN was enhanced significantly in both groups, but in favor of the study group (p < 0.001) over the control group (p = 0.046). Both MVIC and total score of WOMAC were significantly improved in both groups (p < 0.001). CONCLUSION: Adding static hamstring stretching to quadriceps strengthening exercises provided a substantial effect on mJSW, JSN, and functional abilities in KOA patients.
Keywords: Hamstring stretching, quadriceps strengthening exercise, joint space narrowing, joint space width, knee osteoarthritis
Abstract: BACKGROUND: It is unknown whether a session of isometric handgrip (IHG) exercise can influence the blood pressure of hypertensive and normotensive individuals. OBJECTIVE: To compare post exercise hypotension among groups with different resting blood pressure (BP) levels. METHODS: 56 Malay male volunteers (12 normotensive, 14 pre-hypertensive, 19 hypertensive stage 1, and 11 hypertensive stage 2) completed four sets of 2-minute isometric handgrip exercises at 30% of their maximum handgrip contraction with a one-minute break between the sets. Systolic BP (SBP), diastolic BP (DBP), pulse pressure (PP), mean arterial pressure (MAP), resting heart rate…(RHR), and handgrip strength (HGS) were measured before and after an hour of IHG exercise. A paired sample t -test, one-way ANOVA, and two-way repeated measure ANCOVA were used to examine the data. RESULTS: All parameters, except RHR and HGS, were significantly changed following the exercise across the BP groups. The SBP, MAP, and HGS were greatly reduced among hypertensive stage 1 (SBP = - 6.3 ± 0.6 mmHg; MAP = - 4.8 ± 1.1 mmHg; HGS = - 6.8 ± - 0.4 mmHg) compared to other groups. Meanwhile, the most DBP was reduced among hypertensive stage 2 (mean = - 5.2 ± 0.6 mmHg). CONCLUSIONS: The current study discovered a significant reduction in BP among hypertensive stage 1 and 2 individuals after a session of IHG exercise.
Abstract: BACKGROUND: The quantitative recruitment of motor units depends on specific demands, including movement velocity. DNA microarrays differ according to sex, and these sex-related differences affect the fiber type composition. OBJECTIVE: The aim of this study is to demonstrate inter-sex differences in the isokinetic parameters, isokinetic phases, and muscle activities and to investigate the correlation between muscle activity and isokinetic data. METHODS: A total of 41 healthy adults (20 male, 21 female) performed concentric knee extension at angular velocities of 60 ∘ /s, 180 ∘ /s, and 240…∘ /s. The outcome measures consisted of the isokinetic peak moment (PM), normalized PM (PM/BW), total work, and power, alongside the acceleration, iso-speed and deceleration, sub-phases. Muscle activity was recorded from the rectus femoris, vastus lateralis, and vastus medialis using surface EMG. RESULTS: There were significant two-factor main effect and interaction between sex and angular velocity on the power of knee extension and isokinetic phase (p < 0.05). As the velocity increased, the increase in power of males was greater than that of females. In contrast, with the increase in velocity, PM, PM/BW, and total work decreased, but no significant interaction was observed between velocity and sex. At high velocity, males showed higher acceleration ability than females. CONCLUSION: The sex-dependent responses to velocity were more affected by differences in total movement time than force production. Fast isokinetic exercise should consider the acceleration ability rather than the ability to produce force.
Keywords: Isokinetic contraction, sexual difference, fast speed, acceleration phase, knee biomechanics
Abstract: BACKGROUND: Mounting evidence has demonstrated functional and cognitive-related benefits after Instability Resistance Training (IRT) in individuals, healthy as wellas patients presenting with neurological disorders. However, whether IRT may play a significant role in the postural control of older adults has not been established. OBJECTIVE: To evaluate the effects of 12- weeks of IRT on static postural control of older adults with subjective cognitive impairment. METHODS: In this randomized controlled trial, a total of 67 participants (aged 65 years and older) were randomly assigned to either 12 weeks of IRT (n =…22), traditional resistance training (RT) (n = 23), or a health education control group (CON) (n = 22). Static postural control was assessed using a force platform that recorded the displacement amplitude of the center of pressure (CoP) in the anteroposterior (AP) and mediolateral (ML) directions in bipedal support (30 seconds) with eyes open and closed. RESULTS: All groups increased AP displacement in the conditions of eyes open and closed. During the eyes-closed condition, only the IRT group increased the ML displacement. No between-group differences were detected in any postural control (p > 0.05). CONCLUSIONS: 12 weeks of IRT does not improve the static postural control in older adults with cognitive impairment.