Isokinetics and Exercise Science - Volume 29, 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 AND OBJECTIVE: Muscle weakness is among the most common and obvious impairments in older adults and individuals with neurologic disorders. Although impairments in muscle strength are typically characterized using performance measures, the impairments have also been described using patient or observer-report. The objective of this review was to summarize literature describing use of a patient-report instrument, the Strength Domain (SD) of the Stroke Impact Scale (SIS), to grade strength impairments. METHODS: Peer-reviewed literature reporting SD scores for the SIS was identified using computerized searches of the CINAHL, PubMed, and Scopus databases followed by hand searches.…Potentially relevant articles were then mined for data on the participants tested, the SIS version used, scores documented, and clinimetric properties reported. RESULTS: Sixty-five articles were judged appropriate based on inclusion and exclusion criteria. The articles involved more than 7000 residents of 22 countries. All articles focused on individuals with stroke (usually chronic), although one also included community-dwelling adults without stroke. The SIS version used was frequently unreported, but 3.0 was version most often specified. For articles reporting SD scale scores the mean ranged from 19.7 to 85.5. Construct (known groups, convergent, and discriminant) validity of the SD was supported by the literature as was its internal consistency and test-retest reliability. Responsiveness of the SD was evinced by numerous studies showing increases in SD scores with time or accompanying effective interventions. However, only one study indicated responsiveness using an anchor-based statistic. CONCLUSIONS: The SD of the SIS is a well-established and mostly clinimetrically sound patient-report measure of paretic limb strength among individuals with stroke. Its use with individuals with weakness accompanying aging or diagnoses other than stroke remains to be substantiated.
Abstract: BACKGROUND: The abductor hallucis (AbH) is a key muscle in the stability of the foot by supporting the medial longitudinal arch (MLA). Individuals with flat foot show a flattening of the MLA with a decreased selective AbH activity relative to the other foot extrinsic muscles during functional movement. OBJECTIVE: To examine the selective muscle activity of the abductor hallucis (AbH) during single-leg mini-squat (SMS) in subjects with flat foot and normal individuals. METHODS: Twenty-four healthy adults (13 men and 11 women) with flat or normal feet participated in this study. All subjects performed single minisquat…(SMS), and data were collected using sEMG from the AbH, TA, and GCM during SMS. RESULTS: An inter-gender comparison of the EMG data revealed no difference. The EMG activity of the AbH in individuals with flat foot was significantly lower than that of individuals with normal feet. Moreover, the AbH/TA ratio in subjects with flat foot, , was significantly lower than that in subjects with normal feet. CONCLUSION: In a clinical setting, clinicians should focus on strengthening exercises of the AbH muscle due to reduced activation of the AbH muscle in individuals with flat foot. The selective muscle activity of the AbH muscle during SMS should be emphasized.
Abstract: BACKGROUND: Few studies have reported the contribution of isometric-specific exercise of the biceps brachii muscle to increased strength under manual fixation of the scapula. OBJECTIVE: To investigate the activation amplitude of the biceps brachii (BB), serratus anterior (SA), and upper trapezius (UT) in a supine lying posture based on various exercise conditions. METHODS: The EMG activity of BB, SA, and UT was measured in 25 healthy adults while performing maximal elbow flexion exercise with or without manual stabilization of the scapula in two different loading conditions. RESULTS: Muscle activation of the…BB was significantly greater when performed with manual fixation of the scapula under the wrist-loading exercise condition (p < 0.05) but manual fixation of the scapula or absence thereof did not have an effect. Elbow flexion force was significantly increased when applying manual fixation to the scapula in both the hand and wrist-loading exercise conditions (p < 0.05). There were no interaction effects between exercise conditions and manual fixation (with or without) in any of the EMG activation values (p > 0.05). CONCLUSION: Manual stabilization of the scapula is a useful therapeutic technique to increase BB strength. Such an intervention may also be indicated for accurate strength measurement of this muscle.
Keywords: Biceps brachii, manual stabilization, strength training
Abstract: BACKGROUND: Isokinetic evaluation is considered the gold standard in muscle strength measurement due to its sensitivity, intra-dynamometer reproducibility and usefulness in the injury prevention screening and follow up of subjects with musculoskeletal pathologies, neurological disease or after surgical operation. However, can one switch among different isokinetic dynamometers for the purpose of knee muscles evaluation? OBJECTIVES: To comprehensively evaluate the compatibility of the isokinetic short concentric and eccentric strength evaluation protocol and of the fatigability resistance evaluation between three different isokinetic devices. METHODS: Eighteen recreationally active men underwent three isokinetic knee testing sessions on…three different isokinetic devices with 7–10 days of rest between each session. Relative (Pearson’s r product-moment correlation coefficient – PCC) and absolute (standard error of measurement – SEM, Cohen effect sizes (d) and probabilistic inferences – MBI) parameters of reproducibility were determined to assess the inter-dynamometer agreement. RESULTS: For the short concentric and eccentric strength evaluation protocol, the extensors in concentric mode and the flexors in eccentric mode can be compared (eventually with transposition formulas provided) between Biodex, Con-Trex and Cybex (almost all PCC ⩾ 0.80). The DCR could be compared between Con-Trex and Cybex and between Biodex and Cybex pairs (eventually with transposition formula provided). For the fatigability resistance evaluation protocol, the total sum can be compared for extensors (eventually with transposition formulas provided) for PM for all dynamometer pairs considered and, in the case of MW, only for Biodex and Con-Trex (PCC ⩾ 0.80). CONCLUSIONS: Only some of the parameters derived either from the short concentric and eccentric strength evaluation protocol or the fatigability resistance evaluation protocol may be interchangeable providing transposition formulas are applied. Otherwise, isokinetic findings are largely system-dependent save some specific instances.
Abstract: BACKGROUND: During one-leg standing (OLS), optimum activity of the gluteus medius (Gmed), multifidus (MF), and quadratus lumborum (QL) muscles relies upon maintaining neutral lumbopelvic alignment. However, no studies have examined how using pressure biofeedback during OLS affects the activity of these muscles and the concomitant alignment of the pelvis and trunk. OBJECTIVES: The purpose of this study was to investigate the effect of pressure biofeedback on the activity of the Gmed, MF, and QL and the femoropelvic and trunk lean angles during OLS. METHODS: Twenty-four healthy males performed OLS with (PB+…) and without (PB- ) pressure biofeedback. For all OLS conditions, a pressure sensor was placed between the lateral surface of the humerus on the non-supporting side and the wall. Under the PB- condition, participants performed preferred OLS while the examiner measured the maximum pressure caused by trunk lean. Under the PB+ condition, participants were asked to perform at a threshold of 50% of the maximal pressure (PB+ 1 condition) and with minimal change in pressure (PB+ 2 condition). Muscle activities of MF, QL, and Gmed as well as the femoropelvic and trunk lean angles were measured under various OLS conditions. RESULTS: The activity of the Gmed, MF, and QL was greater under both PB+ conditions than under the PB- condition (p < 0.05). Also, both PB+ conditions resulted in a greater femoropelvic angle and reduced trunk lean angle. There were no significant differences in muscle activity, femoropelvic angle, or trunk lean angle between PB+ 1 and PB+ 2 (p > 0.05). CONCLUSIONS: These results suggest that pressure biofeedback is a useful modality for increasing the activity of the Gmed and trunk muscles, especially the MF muscle on the non-supporting leg side, and for preventing compensatory movements such as trunk deviation and pelvic lateral deviation during OLS.
Abstract: BACKGROUND: A method of measurement of voluntary activation (VA, percent of full muscle recruitment) during isometric and isokinetic concentric contractions of the quadriceps femoris (QF) at 60 ∘ /s and 120 ∘ /s was previously validated. OBJECTIVE: This study aimed to quantify the test-retest minimal real difference (MRD) of VA during isometric (ISOM) and isokinetic concentric contractions of QF (100 ∘ /s, ISOK) in a sample of healthy individuals. METHODS: VA was measured through the interpolated twitch technique. Pairs of electrical stimuli were delivered…to the QF at 40 ∘ of knee flexion during maximal voluntary contractions. Twenty-five healthy participants (20–38 years, 12 women, 13 men) completed two testing sessions with a 14-day interval. VA values were linearized through logit transformation (VA l ). The MRD was estimated from intraclass correlation coefficients (model 2.1). RESULTS: The VA (median, range) was 84.20% (38.2–99.9%) in ISOM and 94.22% (33.8–100%) in ISOK. MRD was 0.78 and 1.12 logit for ISOM and ISOK, respectively. As an example, in terms of percent VA these values correspond to a change from 76% to 95% and from 79% to 98% in ISOM and in ISOK, respectively. CONCLUSIONS: The provided MRD values allow to detect significant individual changes in VA, as expected after training and rehabilitation programs.
Keywords: Voluntary activation, isokinetic, quadriceps, minimal real difference, rehabilitation
Abstract: BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured…during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.
Abstract: BACKGROUND: The evaluation of postural trunk muscle function is a critical component of clinical assessment in patients with musculoskeletal pain and dysfunction. Postural activation of the trunk muscles has been evaluated by various methods. This study evaluates the correlation between subjective assessment of postural trunk muscle function with an objective measurement of abdominal wall expansion. METHODS: Twenty-five healthy participants (16 women, 9 men, age 22.4 years) were assessed. The subjective assessment was performed by two experienced Dynamic Neuromuscular Stabilization (DNS) clinicians evaluating the quality of trunk stabilization using five postural stability tests through palpation and observation.…Interrater reliability was determined using an intraclass correlation coefficients (ICC). Objective measurement was performed using a new device (DNS Brace) which externally measures abdominal wall pressure. Spearman rank correlations were calculated for both palpation and observation measures with DNS Brace data. RESULTS: The interrater reliability (ICC2,k) estimates demonstrated moderate reliability in palpation measures for three DNS tests: Hip flexion test, Diaphragm test, & Intra-abdominal pressure regulation test (IAPRT) (ICC = 0.645–0.707). For observation measures, good reliability was found in IAPRT (ICC = 0.835), and three tests demonstrated moderate reliability: Hip flexion test, Diaphragm test, & Breathing Stereotype (ICC = 0.577–0.695). Correlation analysis demonstrated several moderate to strong correlations between palpation and DNS brace values (Assessor 1): IAPRT, r s = 0.580, p = 0.002, Diaphragm test, r s = 0.543, p = 0.005, (Assessor 2): IAPRT, r s = 0.776, p < 0.001, Breathing Stereotype, r s = 0.625, p = 0.001, Diaphragm test, r s = 0.519, p = 0.008, Hip Flexion test, r s = 0.536, p = 0.006, and Arm Elevation test, r s = 0.460, p = 0.021. For observation, several moderate correlations were demonstrated with DNS brace values (Assessor 1): Arm Elevation test, r s = 0.472, p = 0.017, (Assessor 2) Diaphragm test, r s = 0.540, p = 0.005, IAPRT r s = 0.475, p = 0.016, Hip Flexion test, r s = 0.485, p = 0.014, and Arm Elevation, r s = 0.451, p = 0.024. CONCLUSION: Based on inter-rater reliability and DNS brace correlations with trained DNS professionals, the IAPRT, Diaphragm test, and Hip Flexion test may prove useful when assessing asymptomatic individuals. More research is needed in order to establish the utility of DNS brace and clinical testing both in asymptomatic and back pain populations. DNS tests must be supplemented by further examinations for definitive clinical decision making.
Abstract: BACKGROUND: Strength-power tests are commonly used to monitor performance improvement and to assess preparedness for competition in weightlifters. Previous studies were limited to male weightlifters, consisted of a small number of tests, or used small samples of female weightlifters. OBJECTIVE: The purpose of this study is to determine the strongest indicators of weightlifting performance (WPER) and to reveal the relationships between competition performance and strength-power tests in junior female weightlifters. METHODS: Forty-two female weightlifters (age: 17.8 ± 2.3 years, body mass: 56.6 ± 8.1 kg; height: 156.1…± 5.8) participated in this study. Participants were tested on a series of performance indicators including Wingate anaerobic power (lower and upper body), isokinetic leg force, vertical jumps, handgrip strength, and isometric leg strength following a national weightlifting competition. Competition performance was calculated with the Sinclair equation. Pearson correlation analysis was used to reveal the relationships between strength-power variables and Sinclair score, and Ridge regression analysis was used to determine the strongest indicators of WPER. RESULTS: The main results showed that Wingate leg peak power (L-PP) and countermovement jump height (CMJ) were the strongest indicators for WPER. They accounted for 74% of the common variance. Additionally, there was a significant correlation between strength-power variables (r = 0.41–0.846) and Sinclair score. CONCLUSIONS: This study’s findings suggest that the strongest predictors of WPER are L-PP and CMJ, and these tests can be used to monitor WPER in junior female weightlifters.
Abstract: BACKGROUND: The inability of athletes to train or the decrease in the intensity and frequency of training may cause athletes to lose performance. Particularly in view of the current COVID-19 pandemic, maintaining strength outside the normal framework provides an advantage to athletes for the next competitions. OBJECTIVE: To compare the CrossFit Barbara which can be applied easily at home during the off-season or some situations such as the epidemic limitation to classic resistance training methods used to maintain the strength performance of national kickboxers. METHODS: Forty-three national kickboxers, CrossFit (CF, n =…22), and resistance training (RT, n = 21), participated in this study. While CF performed 20 pull-ups, 30 push-ups, 40 sit-ups, and 50 squat exercises, RT performed bench press, lat pull down, leg press, biceps curl, and triceps extension exercises twice per week for six weeks. Before and after the six weeks, the following variables were measured; body mass (BM) and body fat percentage (FP), VO 2max , bench press (BP), squat (SQ), leg strength (LS), hand grip strength (HGS), pull-up, push-up and counter movement jump (CMJ). RESULTS: BP (p < 0.001, F = 41.125, η p 2 = 0.501), SQ (p < 0.001, F = 26.604, η p 2 = 0.394), LS (p < 0.001, F = 15.234, η p 2 = 0.271), push-up (p < 0.001, F = 31.978, η p 2 = 0.438) and pull-up (p < 0.001, F = 24.410, η p 2 = 0.373) values changed significantly in group-time interaction between CF and RT groups, while there was no significant difference for the BM (p = 0.198, F = 1.715, η p 2 = 0.040), Fat (p = 0.265, F = 1.279, η p 2 = 0.030), HGS (p = 0.665, F = 0.190, η p 2 = 0.005, CMJ (p = 0.054, F = 3.946, η p 2 = 0.088) and VO 2max (p = 0.747, F = 0.106, η p 2 = 0.003). Furthermore, according to the before and after study values, BP, SQ, LS, and CMJ decreased significantly (p < 0.05) while BM, FP, HGS, VO 2max , pull-up and push-up variables did not in the CF (p > 0.05). In the RT, the pull-up and push-up variables decreased significantly (p < 0.05) while there was no significant difference for BP, SQ, LS, HGS, VO 2max , body mass, body fat percentage and CMJ (p > 0.05). CONCLUSION: CF Barbara workout was more effective in maintaining strength endurance performances, and RT in maintaining maximum strength performances. According to the individual performance needs of athletes, reasonable training method can be used to prevent performance decrement in the strength domain.
Keywords: Combat sports, exercise, functional training, loss of performance, power