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: Rotator cuff weakness is considered an important risk factor for shoulder injuries in volleyball. OBJECTIVE: To evaluate association of shoulder preseason strength status with shoulder injury occurrence in subsequent season. METHODS: Volleyball players (N = 181; 99 men) from Slovenian 1 st and 2 nd national league volunteered to participate in this prospective cohort study. Preseason isokinetic testing of the shoulder was conducted at 60 ∘ /s in the concentric mode of contraction over a RoM…of 60 ∘ with five repetitions of internal (IR) and external (ER) rotation. During the subsequent season the players reported shoulders injuries through a weekly questionnaire. RESULTS: During the season we have registered 14 (7.7%) shoulder injuries (10 in men). All injuries affected the dominant shoulder. There was significant preseason weakness of ER and lower ER/IR strength ratio in players with shoulder injury. Normal strength ratio ER/IR was a significant protective factor (Exp (B) = 0.217, 95% C.I. 0.058–0.811) for shoulder injury occurrence when controlled for sex and previous injury. CONCLUSIONS: The inclusion of systematic strengthening of the external rotators of the shoulder is necessary, especially for male volleyball players, as part of preventive measures for the prevention of shoulder injuries.
Abstract: BACKGROUND AND OBJECTIVE: Numerous studies have addressed the relationship between paretic knee extension strength and comfortable walking speed after stroke. However, the correlations reported are highly variable. This review sought to summarize the correlational data using meta-analysis. METHODS: Relevant literature was identified via a search of 3 bibliographic databases. Articles were screened and perused for inclusion. Included articles were examined for information on the sample studied, procedures for measuring strength and gait speed, and correlations reported between the 2 variables. Meta-analysis was used to calculate a summary correlation. RESULTS: Of 299 unique articles,…18 met inclusion criteria. Articles were diverse in regard to samples studied, procedures described, and correlations reported. Meta-analysis using data from all included studies revealed a summary correlation of 0.51. For studies using hand-held or isokinetic dynamometry, the summary correlation was 0.46 and 0.59 respectively. CONCLUSIONS: This study provides a better indication of the correlation between paretic knee extension strength and comfortable gait speed than individual studies. The correlation is high enough to provide support for the routine measurement of paretic knee extension force for individuals who have experienced a stroke.
Abstract: BACKGROUND: The effects of whole-body vibration training (WBVT) with same frequency and different amplitudes on bone mineral density (BMD) in the elderly is not reported. OBJECTIVE: To compare the effect of 45-Hz WBVT with different amplitudes on the BMD in elderly women. METHODS: Age-, height-, and weight-matched patients were assigned to a low-amplitude group (n = 19, amplitude of 2 mm), medium-amplitude group (n = 18, amplitude of 3 mm), high-amplitude group (n = 19, amplitude 4 mm),…and control group (n = 20). The WBVT was conducted for 24 weeks in the three amplitude groups. The BMD at lumbar vertebrae L 2 - 4 and the proximal femur was measured at 0 and 24 weeks. RESULTS: The BMD at lumbar vertebrae L 2 - 4 was higher in the high-amplitude group than in the low-amplitude and middle-amplitude groups, and the BMD of the greater trochanter was significantly higher than that in the low-amplitude group (p < 0.05). The BMD of the greater trochanter was significantly higher in the middle- than low-amplitude group (p < 0.05). CONCLUSION: A higher amplitude should be considered when WBVT is performed in elderly patients to increase bone density and prevent osteoporosis.
Keywords: Whole-body vibration training, amplitude, frequency, elderly women, bone mineral density
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: Knee osteoarthritis (KOA) is one of the most common chronic diseases impacting millions of elderly people. OBJECTIVES: The study compared the effects of two intensities of partial blood flow restriction (BFR) with low-intensity resistance training on quadriceps strength and cross-sectional area (CSA), and pain in people with knee osteoarthritis (PwKOA). METHODS: Thirty-five PwKOA, aged 50–65, participated. Quadriceps CSA was measured by ultrasonography, quadriceps strength – by isokinetic dynamometry and pain by VAS. These outcome variables were obtained at the beginning of the study and re-evaluated eight weeks after the intervention.…RESULTS: An interaction effect was present for quadriceps CSA (P = 0.042) and quadriceps strength (P = 0.006), showing that using 70% of total occlusion pressure with 30% 1RM had a more significant effect. Knee pain improved significantly through the main effect of BFR (P < 0.001), and low-intensity resistance training (P = 0.011). Pain improved more at 70% of total occlusion pressure, with 30% of 1RM (2.5 ± 1.06) than 50% total occlusion pressure with 10% of 1RM (5.77 ± 1.46). CONCLUSION: A combination of 70% of total occlusion pressure with 30% 1RM could be beneficial in PwKOA in improving pain, and increasing the quadriceps strength. The changes in the quadriceps strength could be a predictor for knee pain.
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 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 observerreport. The objective of this review was to summarize literature describing use of a patientreport 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 wellestablished 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 difference between isokinetic eccentric to concentric strength ratios at high and low velocities (DEC) is a powerful tool for identifying submaximal effort in other muscle groups but its efficiency in terms of the wrist extensors (WE) and flexors (WF) isokinetic effort has hitherto not been studied. OBJECTIVE: The objective of the present study is to examine the usefulness of the DEC for identifying suboptimal wrist extensor and flexor isokinetic efforts. METHODS: Twenty healthy male volunteers aged 20–40 years (28.5 ± 3.2) were recruited. Participants were instructed to exert…maximal and feigned efforts, using a range of motion of 20 ∘ in concentric (C) and eccentric (E) WE and WF modes at two velocities: 10 and 40 ∘ /s. E/C ratios (E/CR) where then calculated and finally DEC by subtracting low velocity E/CR from high velocity ones. RESULTS: Feigned maximal effort DEC values were significantly higher than their maximal effort counterparts, both for WF and WE. For both actions, a DEC cutoff level to detect submaximal effort could be defined. The sensitivity of the DEC was 71.43% and 62.5% for WE ad WF respectively. The specificity was 100% in both cases. CONCLUSION: The DEC may be a valuable parameter for detecting feigned maximal WF and WE isokinetic effort in healthy adults.
Abstract: BACKGROUND: Active straight leg-raise (ASLR) is often performed to strengthen abdominal muscles. The correct execution and maximum benefit of the ASLR can be achieved using abdominal hollowing (AH) and abdominal bracing (AB) exercises. OBJECTIVE: To compare the effects of AH and AB on transverse abdominis (TrA), internal oblique, and external oblique thicknesses, as well as on the pelvic rotation angle, in healthy women during active ASLR. METHODS: The participants in this study were assigned randomly to either the AH (n = 15) or AB groups (n =…15). During ASLR, abdominal muscle thickness was measured using ultrasound and pelvic rotation was measured using a Smart KEMA device. Each trial was repeated three times for 5 s each. RESULTS: The thickness of the TrA was significantly greater during ASLR with AH than during ASLR with AB (p < 0.001). In contrast, there was no respective significant change in the thickness of the external oblique (p > 0.0.311) or internal oblique (p > 0.818). Pelvic rotation angle was significantly reduced during ASLR with AB, compared with ASLR with AH (p < 0.018). CONCLUSIONS: We recommend that AH be performed for the selective contraction of TrA during ASLR, and that AB be performed for the prevention of the pelvic rotation during ASLR. Therefore, AH and AB should be separately done in stabilization exercises.
Abstract: BACKGROUND: More practical and less fatiguing strategies have been developed to accurately predict the one-repetition maximum (1RM). OBJETIVE: To compare the accuracy of the estimation of the free-weight bench press 1RM between six velocity-based 1RM prediction methods. METHODS: Sixteen men performed an incremental loading test until 1RM on two separate occasions. The first session served to determine the minimal velocity threshold (MVT). The second session was used to determine the validity of the six 1RM prediction methods based on 2 repetition criteria (fastest or average velocity) and 3 MVTs (general MVT of 0.17…m⋅ s - 1 , individual MVT of the preliminary session, and individual MVT of the validity session). Five loads (≈ 2540557085% of 1RM) were used to assess the individualized load-velocity relationships. RESULTS: The absolute difference between the actual and predicted 1RM were low (range = 2.7–3.7%) and did not reveal a significant main effect for repetition criterion (P = 0.402), MVT (P = 0.173) or their two-way interaction (P = 0.354). Furthermore, all 1RM prediction methods accurately estimated bench press 1RM (P ⩾ 0.556; ES ⩽ 0.02; r ⩾ 0.99). CONCLUSIONS: The individualized load-velocity relationship provides an accurate prediction of the 1RM during the free-weight bench press exercise, while the repetition criteria and MVT do not appear to meaningfully affect the prediction accuracy.