Isokinetics and Exercise Science - Volume 26, issue 1
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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: Isokinetic dynamometry is widely considered the gold standard in mechanical muscle performance testing. Invariably, the moment-position raw data obtained from the dynamometer is directly analysed although kinematic inaccuracies may inherently exist. OBJECTIVE: To quantify the differences between two processing methods of isokinetic raw data: one based on the device’s own software and one using a hybrid kinematic procedure. METHODS: Seventy-six healthy male participants performed unilateral concentric knee extensor (Qcon) (90 ∘ ROM) and eccentric knee flexor (Hecc) tests (110 ∘ ROM) at 150 ∘…/s. The knee angles were recorded by two high-speed cameras per body side. RESULTS: Compared to isokinetic data, kinematic analysis revealed reduced knee ROM of 17 ∘ for Qcon and of 21 ∘ for Hecc. Thus, the mean ‘isokinetic’ angular velocity declined to 121 and 122 ∘ /s, respectively. The angles of peak moment changed significantly (- 5 ∘ for Qcon, + 20 ∘ for Hecc). Contractional work decreased (- 20%) only for Qcon. The moments and angles derived from analysis of the DCR at the equilibrium point (DCRe) rose by 7% and 20% respectively when the isokinetic raw data were linked with kinematic data. The comparison of both processing methods revealed very high (R 2 = 91%) and high (R 2 = 69%) relationships for DCRe moments and angles. CONCLUSIONS: Isokinetic raw data comprise kinematic inaccuracies caused by axis misalignment, evasive movements and anatomical features. Although a hybrid kinematic procedure is more time-consuming, it may enable a more valid clinical interpretation of the test findings.
Abstract: BACKGROUND: Blood flow restriction (BFR) resistance exercise often elicits additive response of muscle activation. It is not clear whether local vibration (LV)-induced involuntary muscle contraction plus BFR would elicit an additive response of muscle activation. OBJECTIVE: To investigate the effects of LV exercise with and without BFR on muscle activation. METHODS: Eight physically inactive males were randomly assigned to a sequence of LV (0.45 mm amplitude, 35 Hz sinusoid, lasting 1 min) treatments on unilateral antagonistic muscle groups, including the upper arm (biceps and triceps), the calf (gastrocnemius, GAS; tibialis anterior, TA) and the…thigh (rectus femoris, RF; biceps femoris, BF), in a repeated-measures counterbalanced design, with a 5-min interval separating the treatments. The LV treatments on each of the limbs included one bout of LV and one bout of LV + BFR (inflated to 200 mmHg) in a counterbalanced order. RESULTS: Only the RF and biceps in the measured muscles showed greater electromyography (EMG) values during LV + BFR than those during LV (p < 0.05). CONCLUSIONS: LV + BFR elicits an increase in EMG amplitude in some muscles, with obviously greater values in the RF for the thigh and in the biceps for the upper limb.
Keywords: Cuff, electromyography, thigh, upper arm
Abstract: BACKGROUND: There is a growing interest in identifying markers of pulmonary function that are predictive of peripheral muscle dysfunction in chronic obstructive pulmonary disease (COPD); however, studies of this relationship have yielded contradictory results in the literature. OBJECTIVES: To evaluate the strength and endurance of the quadriceps and hamstring muscles according to gender and to evaluate the associations between lower limb muscle function and lung function, health-related quality of life (HRQoL) and 25-hydroxivitamin D3 (25(OH)D 3 ) levels in patients with COPD. METHODS: Forty-two patients with COPD and 42 matched…healthy controls underwent knee isokinetic dynamometry at 75 and 240 ∘ /s as well as isometric handgrip strength testing. All patients underwent pulmonary function tests and measurement of 25(OH)D 3 . HRQoL was evaluated using the COPD Assessment Test (CAT), the 36-Item Short-Form Health Survey (SF-36) and the Saint George’s Respiratory Questionnaire (SGRQ). RESULTS: Most isokinetic parameters showed differences between males and females as well as between COPD patients and controls; the greatest differences were observed among females with COPD and their matched controls. The strongest correlations were observed between the isokinetic parameters and the SF-36 physical component summary (PCS) and SGRQ and pulmonary function variables, especially at the higher velocity. At this velocity, the agonist/antagonist ratio was positively correlated with the SF-36 PCS (r = 0.65), 25(OH)D 3 levels (r = 0.76) and forced expiratory volume in one second (r = 0.65) and was negatively correlated with the CAT (r = - 0.53) and the SGRQ (r = - 0.64) (P < 0.001 for all correlations). The associations between the isokinetic parameters and 25(OH)D 3 levels were stronger when endurance was tested. CONCLUSIONS: Patients with COPD show a reduction in both strength and endurance, especially in females. The relationships between muscle function, lung function, HRQoL and 25(OH)D 3 levels are most striking when endurance and hamstring/quadriceps muscle balance are tested. In COPD, forced expiratory volume in one second is the strongest marker of lung function that predicts muscle dysfunction.
Keywords: COPD, musculoskeletal dysfunction, respiratory function tests, quality of life, vitamin D
Abstract: OBJECTIVE: This study compared the effects of dynamic and static core training programs on soccer related speed, agility. anaerobic power tests, core stability tests and body composition measurements. METHODS: A Static (n = 14) and Dynamic (n = 13) training groups performed three 30 min sessions per week for 8 weeks while attending scheduled soccer training sessions. RESULTS: Sprint (10–30 m), agility (505 and Arrowhead), vertical and standing long jump scores did not increase in any groups. Neither group demonstrated difference in body…composition measurements for repeated test scores and between group comparisons. Experiment groups improved dynamic and static core stabilization test scores while Control group did not change. CONCLUSIONS: The results indicate that both training types improved movement related measures of core stability which did not transfer into any anaerobic skills and body composition. Thus core stability training is not generating sufficient stimulus to improve power and strength dependent performance skills such as sprint and agility and therefore may not constitute a cardinal component in soccer conditioning programs.
Abstract: OBJECTIVE: To determine the effects of kicking leg preference on the bilateral leg strength asymmetries of amateur football players. METHODS : Thirty-four right-dominant (RD) and twenty-three left-dominant (LD) amateur football players volunteered to participate in the study. Squat and countermovement jump, standing long jump, and isokinetic knee strength (at 60, 180 and 300 ∘ /s) were tested with respect to inter-limb asymmetry index (ASI). RESULTS: There were significant differences in horizontal jump and H/Q ratio at 60 ∘ /s between DL and NDL in all football players. There…were also significant differences in standing long jump, hamstring peak torque at 180 ∘ /s and H/Q ratio at 60 ∘ /s in the LD football players (p < 0.05). Moreover, the LD group had greater percentage of subjects with ASI > 15% for standing long jump, hamstring peak torque at 180 ∘ /s. Furthermore the percentage of subjects with H/Q Ratio < 0.60 for 60 ∘ /s was greater in the LD players’ DL. CONCLUSION: Bilateral leg strength asymmetries may be affected by a single leg predominantly in the mobilization workouts. Having higher inter-limb asymmetry index, LD players may be screened and trained to minimize leg strength asymmetries.
Keywords: Bilateral, strength, asymmetry, dominant leg, leg preference
Abstract: BACKGROUND: Research suggests that effect of continuous static stretching on sport performance and/or injury prevention depends on the total stretching volume. OBJECTIVE: To analyze the acute effects of three short duration static stretching interventions of four lower limb muscle groups (15, 30 and 60 seconds per muscle) on the eccentric isokinetic peak force (PF) and peak power (PP) measures obtained during leg press exercise. METHODS: A total of thirteen amateur athletes, 7 men and 6 women, completed four different interventions in a randomized order on separate days: one control (non-stretching) and three static…stretching (SS) interventions (1 × 15 s, 1 × 30 s and 1 × 60-s). After the stretching or control interventions, eccentric isokinetic PF and PP were assessed at two different linear velocities (200 mm/s and 400 mm/s). RESULTS: Measures were compared via a magnitude-based inference analysis. The results of this study showed no significant main effects between intervention-paired comparisons for any PF and PP measures. CONCLUSION: The findings of this study suggest that sport-relevant durations of SS have no effect on eccentric strength and power performance during leg press exercise and hence, the role of SS as a method to reduce the relative risk of injury is questionable.
Keywords: Strength training, isokinetic, force, power
Abstract: BACKGROUND: The high variability in muscle performance, especially in muscle strength, typical of people with multiple sclerosis (PwMS) implies that in order for strength variations to be clinically interpretable, the extent of variability should be properly quantified. OBJECTIVE: To establish the responsiveness of maximal isokinetic strength measurements obtained from the ankle dorsiflexors of PwMS and of a cohort of matched healthy controls. METHODS: Twenty PwMS and 20 healthy controls participated in this study. All subjects underwent a dedicated familiarization session and then three isokinetic testing sessions (Test 1; 1-day retest; 1-week retest) in…which the peak moment (PM) and maximal work (MW) were recorded in the more affected side. RESULTS: PwMS proved significantly weaker than controls (p < 0.00005). The test-retest consistency of the measurements proved high for both groups (all intraclass correlation coefficients > 0.9). Importantly, the smallest real difference (SRD) scores ranged 11.4–19.8% for PwMS and 9.2–14.4% for controls. CONCLUSIONS: The responsiveness of the strength and work findings in this cohort indicates that isokinetic measurements of dorsiflexion performance in PwMS may effectively be employed for detecting the efficiency of an intervention in spite of the fluctuating nature of this disease.
Abstract: BACKGROUND: Posterior shoulder tightness (PST) has been identified as an important factor that causes scapular dyskinesis. Therefore, rehabilitation programs should focus on an intervention involving a posterior shoulder stretch combined with a scapular stabilization exercise (PSSE). However, few studies have investigated the effects of PSSE on rotator cuff (RC) muscle strength in overhead athletes with scapular dyskinesis. OBJECTIVE: To determine the effects of PSSE on RC muscle strength, dynamic control ratio (DCR), range of motion (ROM), and pain. METHODS: Twenty-four adolescent baseball players with scapular dyskinesis were randomly allocated to one of two…groups which trained for 6-weeks. Group I performed PSSE while group II performed same exercises but without stretching (SSE). The isokinetic peak moment/body weight (PM/BW) of concentric and eccentric external rotation (ERc and ERe) and concentric and eccentric internal rotation (IRc and IRe), the DCR (ERe/IRc and IRe/ERc), ROM, and pain were measured in pre- and post-intervention. RESULTS: A time-by-group interaction effect was observed for the concentric and eccentric ER, the DCR, and the ROM only the PSSE group. CONCLUSIONS: PSSE intervention is a more effective program than SSE for improving RC muscle strength and balance, particularly in terms of its ER component and the associated DCR.
Abstract: BACKGROUND: Despite the fact that there is considerable research in gender related differences in athletic performance, limited studies have been found related with the gender differences in repeated sprint ability (RSA). OBJECTIVE: The purpose of this study was to evaluate the gender related differences in RSA. METHODS: Forty team sport athletes participated in this study voluntarily and RSA was determined by a 5 × 6 s cycling RSA test with 24 s recovery. Participants’ peak power (PP), mean power (MP) and performance decrement (PD%) were determined as performance variables. Maximal blood lactate…(La) max , heart rate (HR) max and ratings of perceived exertion (RPE) max were determined as physiological responses. RESULTS: Results indicated higher relative PP and MP for men (p < 0.05) while no significant gender differences was observed in PD% (p > 0.05). Men had higher La max (p < 0.05), while there were no gender differences in HR max and RPE max (p > 0.05). In addition, the highest values was observed in the first sprint for both relative PP and MP regardless of gender and men performed higher than women in each cycle repetitions. CONCLUSIONS: In conclusion gender related differences were observed in RSA except for PD%, HR max and RPE max which indicated that men and women were not different in terms of fatigue resistance and experienced the same physiological strain during the RSA test.