Isokinetics and Exercise Science - Volume 30, issue 2
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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: Pulse oximetry measures heart rate (HR) and percent oxygen saturation (SpO 2 ). For aerobic exercise, whereby cellular oxygen demand and delivery are elevated and maintained for extended periods, HR and SpO 2 values are consistent when measured by pulse oximetry. Yet due to its intermittent nature, HR and SpO 2 values from resistive exercise may exhibit lower data reliability and repeatability. OBJECTIVE: Assess intra-rater reliability and repeatability of pulse oximetry HR and SpO 2 values from two identical resistive…exercise protocols. METHODS: Subjects (n = 32) performed two calf press workouts on a flywheel-based ergometer as HR and SpO 2 were measured before, between sets, and after exercise. Workouts entailed a 4-set 15-repetition protocol separated by 120-second rests. Intra-rater reliability was assessed with intraclass correlation coefficients (ICC). Repeatability was measured by the smallest real difference in absolute and relative terms. RESULTS: ICC and standard error of estimate results for HR ranged from 0.60–0.79 and 9.1–13.0 respectively. SpO 2 ICC and standard error of estimate results ranged from 0.16–0.71 and 1.44–4.33 respectively. Between sets, smallest real difference values tended to be less for HR. CONCLUSIONS: Results demonstrate acceptable intra-rater reliability and repeatability for HR, but not SpO 2 which we attribute to the exercise mode and protocol examined.
Keywords: Heart rate, percent oxygen saturation, steady state
Abstract: BACKGROUND: Bilateral strength asymmetry and fatigue predispose athletes to various injuries and conventional methods appear to be poor predictors of lower extremity muscular performance under NF conditions. OBJECTIVE: The purpose of the study was to compare the conventional Hcon/Qcon (HQR) ratio and the dynamic control ratio (DCR: Hecc/Qcon) under non-fatiguing (NF) and fatiguing (F) conditions and verify the effects of heavy-intensity constant running and cycling exercise on the isokinetic performance. METHODS: Twenty healthy male participants performed running and cycling VO 2 max at work-rate associated with the achievement of VO…2 max (TTE). Isokinetic muscle strength performance was tested at 60 and 180 ∘ /s before and after these sessions with 48-hour intervals. Quadriceps (QFR) and hamstring (HFR) muscle fatigue rates were also calculated during these sessions. Blood lactate concentration was measured before and two-minutes after running and cycling TTE. RESULTS: No between-condition differences were found for the HQR while the DCR decreased significantly at 180 ∘ /s following cycling and running sessions (p < 0.05). Cycling TTE was positively correlated with in dominant (r = 0.535, p = 0.015) and non-dominant (r = 0.446, p = 0.048) QFR. Positive correlations were also found between running TTE and dominant (r = 0.500, p = 0.25) and non-dominant (r = 0.465, p = 0.039) HFR. CONCLUSIONS: The DCR obtained at fast angular velocities following a strenuous exercise seems to be the best indicator of muscle performance while its assessment under F conditions reveals higher ratios compared to NF conditions and conventional methods.
Keywords: Hamstring-to-quadriceps ratio, reproducibility, blood lactate concentration, training load, fatigue
Abstract: BACKGROUND: Vibration training can affect strength improvement. However, the role of the vibration frequency, in terms of knee muscle strength, is unclear. OBJECTIVE: To evaluate the effect of vibration training with the same amplitude and different frequencies on the isokinetic muscle strength of the knee in juvenile football players. METHODS: Juvenile football players were divided into four groups: low frequency (n = 13, 25 Hz), medium frequency (n = 14, 40 Hz), high frequency (n = 14, 50 Hz), and control…(n = 13). The frequency groups completed 12 weeks of weight-free vibration training (three times/week) with the same amplitude (3 mm) but different frequency. RESULTS: Compared with baseline, the peak extension torque of the knee at 60 ∘ /s and 240 ∘ /s increased by 8.4% and 12.9%, respectively, in the medium-frequency group, and by 8.9% and 15.5%, respectively, in the high-frequency group. The extensor endurance (the ability of joint muscle groups to maintain a force output over time) of the knee in the high-frequency group increased by 4.3%. At 12 weeks, the high-frequency group had greater knee extensor endurance than the low- and medium-frequency groups. CONCLUSION: In juvenile football players, weight-free vibration training at 40 Hz and 50 Hz improves peak torque of the knee extensors at 60 ∘ /s and 240 ∘ /s, while training at 50 Hz improves endurance of the knee extensors.
Abstract: BACKGROUND: Some recovery strategies are needed to reduce or eliminate the effect of negative symptoms caused by exercise. OBJECTIVE: The aim of this study was to determine the effect of different types of recovery after single-bout strength exercises on biomarkers of muscle damage, cytokine release and lactate elimination. METHODS: Following familiarization, 10 male volunteers performed four randomized recovery protocols (passive or active recovery with or without compression garments) following a single bout of resistance exercise (squat and deadlift exercises). The blood creatine kinase (CK), lactate dehydrogenase (LDH), interleukine-6 (IL-6), and tumor necrosis factor-alfa…(TNF-α ) values were measured before and after exercise, and after 24, 48, 72 hours. RESULTS: The CK analysis showed that all protocols significantly increased (p < 0.05) CK activity compared to the pre and 24 h post time points. Interestingly, protocol 3 and 4 significantly decreased (p < 0.05) CK activity compared 24 and 72 h post-exercise. LDH, IL-6, and TNF values did not show significant difference (p > 0.05) at the time points tested. CONCLUSIONS: Active recovery is an effective method for reducing the severity and duration of muscle damage and for accelerating the clearance of blood lactate (BLa) following a single bout of strength training. There is no added benefit of using compression garments.
Abstract: BACKGROUND: Handstand is the most important fundamental skill in gymnastics. A gradual and well-balanced increase in muscle loading in a manner is preferred for young beginners and/or recovering gymnasts to safely achieve the muscle strength required to perform a stable handstand. OBJECTIVE: To examine upper limb muscle activity during different levels of handstand training positions. METHODS: This study utilized four different positions for progressive handstand training; namely, the 90, 135, elbow stand, and handstand positions. The activities of eight upper limb muscles (upper, middle, and lower trapezius; serratus anterior; anterior and middle deltoid;…infraspinatus; and latissimus dorsi were measured by surface electromyography (EMG) for each position. The percentages of EMG in each muscle compared to the values during maximum voluntary contraction were calculated and compared between the positions. RESULTS: Muscle activity around the shoulder increased gradually throughout the progression of the four handstand training positions. Furthermore, the muscles required for scapular stabilization, such as the upper and middle trapezius and serratus anterior muscles, were activated at levels similar to those for a handstand without performing this movement. CONCLUSIONS: A progressive handstand training program of four different positions resulted in gradual and well-balanced increases in muscle activity.
Abstract: BACKGROUND: Various interventions have been recommended to increase ankle dorsiflexion range of motion (DFROM); however, few studies have investigated the long-term effects of applying gastrocnemius stretching with talus-stabilizing taping (GSTST). OBJECTIVE: To compare the effects of gastrocnemius stretching (GS) and GSTST on DFROM and balance in subjects with limited DFROM. METHODS: Twenty-six subjects with limited DFROM were randomly allocated to either the GS group (n = 13) or GSTST group (n = 13) for 6 weeks. Maximum DFROM before heel-off during gait, passive…DFROM, posterior talar glide, flexibility of the gastrocnemius, and the lower-quarter Y-balance test (YBT-LQ) were assessed pre-intervention and post-intervention. Two-way repeated-measures analysis of variance was used to compare the changes in variables. RESULTS: The GSTST group had greater maximum DFROM before heel-off, passive DFROM, and posterior talar glide than the GS group. Gastrocnemius flexibility and YBT-LQ scores increased significantly post-intervention in both groups; however, there was no significant difference between the groups. CONCLUSIONS: GSTST is recommend for improving ankle DFROM and balance in subjects with limited DFROM.
Abstract: BACKGROUND: Abnormal foot mechanics in foot over-pronation has an identified relationship with mechanical low back pain (MLBP). OBJECTIVE: To explore the use of short foot exercises (SFEs) as a standalone treatment for MLBP with foot over-pronation. METHODS: Forty-six patients with MLBP (PwMLBP) presenting with and foot over-pronation were analyzed. They were randomized into the SFE (short foot exercise), SFE plus traditional physical therapy treatment (SFE+ TPT), and control (CG) groups. Functional disability and pain level were measured using the Oswestry Disability Index (ODI) and visual analog scale (VAS), respectively. Ultrasonography measured…the cross-sectional area (CSA) of the abductor hallucis (AbdH) muscle. The foot posture and navicular drop (ND) were investigated using the foot posture index-6 (FPI) score and ND test, respectively. RESULTS: The CSA of the AbdH and VAS scores improved significantly (p < 0.001) between the groups, more in the SFE+ TPT group than in the SFE group (p < 0.001). The ND, FPI, and ODI measures improved significantly among the groups (p < 0.001), with no significant difference (p > 0.002) between the SFE and SFE+ TPT groups. The CG did not show significant differences in the outcome measures (p > 0.002). Based on the effect size, SFEs significantly improved all the variables of interest (d > 1). CONCLUSION: SFEs, with or without TPT may offer an effective treatment for PwMLBP with foot over-pronation.
Keywords: Mechanical low back pain, foot overpronation, short foot exercises, navicular drop, abductor hallucis muscle
Abstract: BACKGROUND: Supervised strength training has been shown to promote physiological adaptations in children and youth that can be beneficial to the process of physical growth and developed, and general health status. METHODS: Sixty-three children (9.2 ± 0.5 years old) were randomly assigned to training groups: multi jumps (MJ) (n = 20), sled towing (ST) (n = 21), or uphill running (UR) (n = 22). The following tests were applied before and after each intervention: vertical jump (ABK, CMJ,…SJ), standing broad jump (SBJ), velocity/agility 4 × 10 m, and 20 m sprint test (ST 20m ). RESULTS: After 8 weeks of training, statistically significant changes were found in all study variables for all groups, but with different effect sizes. In the ABK jump, the largest effect size was observed in UR (1.40, 0.97–1.85), while in ST and MJ it was medium (0.67, 0.44–0.98 and 0.48, 0.17–0.82, respectively). Similarly, the effect size in the SJ jump was large for the UR and ST groups (1.10, 0.78–1.51 and 1.30, 0.98–1.64, respectively) and medium in MJ (0.56, 0.24–0.97). However, the magnitude of the effect registered in SBJ was large in MJ (0.80, 0.55–1.15) and medium in UR and ST (0.56, 0.32–0.86 and 0.64, 0.42–1.013, respectively). CONCLUSIONS: All three training programs improve jumping and velocity/agility performance but based on clinical significance, UR and ST methods can be considered more efficient to improve physical performance in children.
Keywords: Exercise training, muscle strength, plyometric exercise, physical education and training
Abstract: BACKGROUND: Low-load resistance training with blood flow restriction (LL + BFR) attenuated delayed onset muscle soreness (DOMS) under some conditions. OBJECTIVE: The purpose of this study examined the effects of reciprocal concentric-only elbow flexion-extension muscle actions at 30% of peak torque on indices of DOMS. METHODS: Thirty untrained women (mean ± SD; 22 ± 2.4 years) were randomly assigned to 6 training days of LL + BFR (n = 10), low-load non-BFR (LL) (n =…10), or control (n = 10). Participants completed 4 sets (1 × 30, 3 × 15) of submaximal (30% of peak torque), unilateral, isokinetic (120 ∘ s - 1 ) muscle actions. Indices of DOMS including peak power, resting elbow joint angle (ROM), perceived muscle soreness (VAS), and pain pressure threshold (PPT) were assessed. RESULTS: There were no changes in peak power, ROM, or VAS. There was a significant interaction for PPT. Follow-up analyses indicated PPT increased for the LL + BFR condition (Day 5 > Day 2), but did not decrease below baseline. The results of the present study indicated LL + BFR and LL did not induce DOMS for the elbow extensors in previously untrained women. CONCLUSION: These findings suggested LL + BFR and LL concentric-only resistance training could be an effective training modality to elicit muscular adaptation without inducing DOMS.
Keywords: Muscle damage, muscle soreness, resistance training
Abstract: BACKGROUND: Lumbar radiological abnormalities (LRA) and trunk muscle weakness are major causes of the low back pain (LBP). We reported that the prevalence of LRA was approximately 90% in middle- and heavyweight-judokas, independent to the occurrence of LBP. However, the trunk muscle weakness, especially the rotators, plays a key role in occurrence of LBP in heavyweight judokas. OBJECTIVE: To examine the trunk muscle strength (TMS) and LRA impact on LBP occurrence in lightweight judokas. METHOD: The strength of the trunk extensors, flexors, and rotators was measured in 32 lightweight male judokas. LBP and…LRA were identified using a questionnaire, X-ray, and MRI. RESULTS: The occurrence rate of LBP and LRA were 40.6% and 62.5%, respectively, without any significant correlation. Among judokas without LRA, TMS of those with LBP were significantly lower than those without LBP (P < 0.05, the extensor; 60 ∘ /s: ES [d] = 1.38, 90 ∘ /s: ES [d] = 0.78, and 120∘ /s: ES [d] = 0.37, flexor; 60 ∘ /s: ES [d] = 1.48, dominant rotator; 60 ∘ /s: ES [d] = 1.66, and 90 ∘ /s: ES [d] = 1.87, non-dominant rotator; 90 ∘ /s: ES [d] = 0.17, and dominant/non-dominant rotator ratio; 90 ∘ /s: ES [d] = 1.55). Moreover, there were significant negative correlations between LBP severity and TMS (P < 0.05, the extensor; 90 ∘ /s: r = - 0.63, dominant rotator; 90 ∘ /s: r = - 0.648, and dominant/non-dominant rotator ratio; 90 ∘ /s: r = - 0.621) in judokas without LRA. CONCLUSION: Weak trunk musculature may be a co-factor in the occurrence of LBP in lightweight judokas without LRA.