Isokinetics and Exercise Science - Volume Preprint, issue Preprint
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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: Relatively little is known about the longitudinal changes in strength and function in the early phase compared to long term outcome following reconstruction of the anterior cruciate ligament (ACL). OBJECTIVE: To assess the isokinetic concentric strength of the knee extensors and flexors as well as the distance jumped in the one-legged hop test in patients before and at 3, 6 and 12 months after (6 and 12 months for the hop test) reconstruction of the ACL. METHOD: Seventy-three men, aged 18–50 years took part in the study. The primary outcome measures were the International Knee…Documentation Committee (IKDC) scores at 3, 6, and 12 months after surgery and one-legged hop test at 6 and 12 months after post-reconstruction. RESULTS: There was a consistent increase in muscular strength between 3 and 12 months post-reconstruction. Fair but significant correlations were found between the IKDC score at 12 months and the peak moment of the knee extensors at 3 and 6 months (r = 0.450 and 0.429, respectively, p = 0.012). 60.2% of the participants satisfied the criteria of successful outcome based on IKDC scores and one-legged hop test at 12 months. The peak moment of knee extensor measured at 3 months after surgery was a significant predictive factor for successful outcome (p = 0.021). Patients in whom muscle strength had recovered well by 3 months after ACL reconstruction were more active in terms of sporting activities and exhibited better dynamic performance at the 1-year follow-up. CONCLUSION: Knee extension strengthening in early phase is crucial to restoring sporting performance after ACL reconstruction.
Keywords: Isokinetic strength, ACL, IKDC score, one-legged hop test
Abstract: OBJECTIVES: There is no consensus regarding the mechanism of strength enhancement of regular whole-body vibration training (WBVT), which involves only neural or neural plus muscular adaptation. This discord could be based on lack of protein supplement to diet in WBVT. This study aimed to clarify the effects of adding protein to the diet on hypertrophy and strength during whole-body vibration training (WBVT). METHODS: Young healty male adults, 20–30 years old were grouped into control (n = 15) and protein groups (n = 14). All experimental subjects…performed WBVT 3 days per week for 12 weeks. During WBVT, the protein group was provided with whey protein (1 g/kg) and the control group was provided with carbohydrate (1 g/kg starch isolate). Baseline measurements (pre-test) were done before the training program started while the last measurements (post-test) took place after the 12-w program. Body fat ratio and lean body mass were measured using bioelectrical impedance and hydrostatic weighing methods. Mid-thigh circumference (cm) and thigh skinfold measurement (cm) were used to calculate leg muscle area. The changes in muscle strength were evaluated by measuring jump height, hand-grip and leg strength. RESULTS: There were significant within-group differences between the post and in pre-training strength values of muscular strength but no between-group differences were noted. There were no changes in leg muscle area, body fat ratio and lean body mass in the control group. CONCLUSION: Protein supplementation does not affect strength and muscle mass after WBVT.
Abstract: BACKGROUND: The palmaris longus (PLM) is a fusiform-shaped muscle that appears in the superficial flexor compartment of the forearm. It has been suggested that PLM is a phylogenetically degenerate metacarpophalangeal joint flexor. OBJECTIVE: The aim of this study was to compare the strength of wrist flexion and extension in healthy volunteers with and without the PLM. METHODS: Sixty-four healthy subjects, 30 men and 34 women, 18–22 years old were enrolled in this study. The database consisted of 128 wrist tests. The inclusion criteria were as follows: sedentary lifestyle, unknown musculoskeletal disorders and right-handedness.…Musculoskeletal ultrasound imaging was used for assessing the presence of PLM. A hand-held digital dynamometer was used to assess the peak force of wrist extension and flexion. Data were analyzed separately for women and men RESULTS: The existence of right-sided PLM was 73.3% in male subjects and 55.9% in female subjects. For men, the strength of wrist flexion was 36.03 ± 13.92 N and 34.24 ± 12.23 N for the right and left side, respectively. For women, the respective strengths were 16.20 ± 7.29 N and 15.26 ± 6.79 N. For both sexes, there was no statistically significant difference between those with and without a PLM (p > 0.05). There was also no significant difference in the agonist/antagonist (flexion/extension) ratio of the wrist between those with and without a PLM in both sexes and sides. CONCLUSIONS: The existence or absence of PLM plays no role in the strength of either the flexors or extensors of the wrist.
Abstract: BACKGROUND: Isokinetic dynamometers measure moment and calculate work and power values, which are generally used to interpret muscle performance. OBJECTİE: This study aimed to determine the differences of peak moment (PM), work, and power between FRoM and calculated valid isokinetic sector (VIS) data to define the possibility of the misinterpretation of isokinetic dynamometer data. METHODS: Fourteen professional male soccer players who had ACL reconstruction were recruited to the muscle strengthening program which was conducted four days a week for six weeks with increasing training intensity each week. Isokinetic muscle peak moment, work, and…power of knee extensors and flexors were measured at angular velocities of 60, 120, 180 and 240 ∘ /s. RESULTS: The results of the standard full-RoM (FRoM) report were compared with the calculated VIS data. Analyses of the FRoM data showed that PM, work, and power values for both extensor and flexor muscle groups improved significantly. However, a comparison of FRoM and VIS data showed significant differences for the work and power values at 120, 180 and 240 ∘ /s. CONCLUSION: The evaluation of FRoM isokinetic data may cause improper interpretations in muscle performance, particularly for contractions with higher angular velocities.
Abstract: BACKGROUND: Little is known regarding the influence of force application during fatigue when the total amount of work is equal. That is, do changes in force applications result in different fatigue mechanisms despite the overall work being the same. OBJECTIVE: The aim of the current study was to examine the effects of alternating forces versus repeated constant force muscle actions on the time course of changes in neuromuscular responses. METHODS: Sixteen adults performed 50-intermittent isometric leg extensions at alternating 40 then 80% maximal voluntary isometric contraction (40/80% MVIC) or repeated constant forces at 60% MVIC. Each…protocol resulted in equal, averaged force across all 50 repetitions. Electromyographic amplitude (EMG RMS), mechanomyographic (MMG) RMS, EMG mean power frequency (MPF), and MMG MPF were recorded from the vastus lateralis. RESULTS: Alternating force protocol resulted in less fatigue-induced changes in neuromuscular responses compared to repeated constant force protocol. The repeated constant force protocol resulted in earlier increases in EMG RMS and MMG RMS as well as earlier decreases in EMG MPF and MMG MPF compared to the alternating force protocol. CONCLUSIONS: Fatigue in occupational, sporting activities, or various fatiguing tasks may be dependent on the order that force is applied.
Keywords: Physical work, loading, work measurement, work physiology, musculoskeletal system
Abstract: BACKGROUND: The ratio of hamstring to quadriceps strength (H/Q), from isokinetic testing, is often used to guide training or rehabilitation. OBJECTIVES: The primary objective was to develop an assessment protocol that produces reproducible H/Q data in a single testing session. METHODS: Twenty-four healthy subjects, 16 women and 8 men, were tested using a reliability study design (2 sessions, 5 repetitions). The main outcome measure was the dynamic control ratio at 60 ∘ /s (DCR60). Testing was also done at 120 ∘ /s, and concentrically at 180 ∘…/s. Generalizability theory was used to determine the reliability (φ ) coefficient and the minimal detectable change MDC, and to extrapolate the data to develop an optimal assessment protocol, ideally using data from only one session. RESULTS: Single-session DCR60 data were reproducible (φ coefficient = 0.868, MDC95 = 0.144) using 5 repetitions, excluding the first repetition from the average. Values were improved by averaging over multiple sessions and repetitions, although little was gained from more than 2 sessions or 5 repetitions. Comparable results were found for testing at 120 ∘ /s. CONCLUSIONS: Reproducible DCR60 values may be derived from a single testing session of the hamstrings (in eccentric mode) and the quadriceps (in concentric mode). We recommend collecting five repetitions, and averaging the data for repetitions 2–5.
Abstract: OBJECTIVE: To describe and compare decreases in grip and knee extension strength accompanying aging. METHOD: Eighty-five community-dwelling women (20 to 79 years of age) participating in the validation phase of the NIH Toolbox for the Assessment of Neurological and Behavioral Function contributed data to this study. Their strength was measured bilaterally-grip with a hand dynamometer and isometric knee extension with an isokinetic dynamometer. Grip and knee extension strength measures of the left and right sides were combined and analyzed. RESULTS: Both combined grip strength and combined knee extension strength decreased with age. The…decreases were significant between the 60–79 year age group and the 20–39 year age group. Strength of the 60–79 year age group, described as a percentage of the 20–39 year age group, was significantly less for knee extension than for grip. CONCLUSION: Grip strength declines less than knee extension strength with age. Grip strength, therefore, may not fully capture the effect of age on muscle strength.
Abstract: BACKGROUND: Assessing players’ leg strength ratios prior to season is important in order to measure performance and identify weaknesses. Leg ratios are calculated by dividing the moment of hamstring by quadriceps. The simple (concentric only) HQ ratio and the dynamic control ratio (DCR) (Hamstring eccentric/Quadriceps concentric) are used to detect asymmetry, knee strength, and bilateral deficit (BD). However, open (OKC) and closed kinetic chain (CKC) tests potentially provide different information regarding muscle strength and balance. OBJECTIVE: The purpose of this study was to measure the abovementioned ratios in male and female amateur rugby union players and…to assess difference between OKC and CKC tests. METHODS: Six males (age = 22.00 ± 2.61 y, height = 172.67 ± 6.12 cm, mass = 80.28 ± 11.13 kg) and 11 females (age = 24.73 ± 3.66, height = 164.00 ± 5.23, mass = 74.00 ± 18.14 kg) rugby union players performed an isometric-mid thigh pull (IMTP) and isokinetic knee extension/flexion at 60 ∘ /s. RESULTS: The non-dominant leg simple ratio (0.81 ± 0.13%) was greater than dominant (0.74 ± 0.14%) while the DCR (0.81 ± 0.14%) was greater than simple ratio (0.73 ± 0.10%). The OKC BD (- 21.00 ± 13.86%) was significantly greater than its CKC counterpart (- 6.76 ± 9.79%) while males’ OKC BD (- 30.55 ± 14.93%) was significantly greater than females’ (- 15.79 ± 10.55%). CONCLUSION: The DCR may be more sport specific when measuring knee strength, while an OKC test is more likely to detect BD due to muscle isolation.
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 reduced the knee’s ROM by 17 ∘ for Qcon and by 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% 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: 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