Isokinetics and Exercise Science

Lower limb strength after stroke, particularly of the more paretic side, is known to correlate with comfortable gait speed. This meta-analysis sought to determine the relative value of 6 muscle group strengths as explanators of comfortable gait speed.

Relevant literature was sought using PubMed, CINAHL Scopus, and a hand search. Information on samples, measurements, and correlations were extracted. Correlational data were subjected to meta-analysis.

Results from 6 studies were consolidated. The summary correlations between paretic lower limb strength and comfortable gait speed ranged from 0.45 to 0.61. Data were highly heterogeneous but did not show publication bias.

The correlation between the lower limb strength and comfortable gait speed strength was moderate. However, it does not provide an adequate explanation to guide clinical practice.

Limited data exist regarding segmental contributions of lower extremity muscles to the swim start performance during different start techniques in young swimmers.

To determine the differences in the kinematic parameters between the grab start (GS) and track start (TS) techniques and assess the interactions between the lower limb muscle strength and swim start performance.

A total of 40 swimmers, 20 girls (age: 13.70 ± 1.80 y, height: 161.65 ± 8.28 cm, body weight: 53.70 ± 8.65 kg) and 20 boys (age: 13.90 ± 1.45 y, height: 160.95 ± 12.70 cm, body weight: 52.95 ± 12.64 kg), 13–16 y of age, at the competitive level were recruited. Ankle, hip, and knee muscles were tested isokinetically at 60 ∘ /s and the tests were spread over 24 h to avoid fatigue. Several elements relating to GS and TS were measured using a motion pick-up video camera.

The angle of entry (EA) at water and knee joint angle (KA) were significantly greater during GS both for boys (EA: 44.18 ± 1.07 ∘ vs. 43.03 ± 1.28 ∘ ; KA: 112.10 ± 15.25 ∘ vs. 107.21 ± 21.13 ) ∘ and girls (45.09 ± 1.28 ∘ vs. 43.36 ± 1.55 ∘ ; KA: 103.08 ± 11.21 ∘ vs. 97.45 ± 19.52 ∘ , p < 0.05). Flight time (FT), flight distance (FD), KA, and flight velocity (FV) were significantly higher for boys both during GS and TS, whereas EA was significantly lower for boys during GS compared to girls ( p < 0.05). Lower limb strength performance was positively significantly correlated with FT, FD, and FV both during GS and TS ( p < 0.05). Hip muscle strength was inversely correlated with the EA both during GS and TS ( p < 0.05). The combination of the knee, ankle, and hip extensor and flexor muscle strengths had a greater effect during GS (35% vs. 29%) in RT, (48% vs. 46%) in FT, (59% vs. 57%) in FD, and (63% vs. 57%) in FV compared to the TS.

Incorporating lower body strength training into the swimming training schedule may improve swim start performance variables during grab start and track start techniques.

An advantage that deadlift (DL) has over back squat (BSQ) is that the latter requires additional equipment (i.e., squat rack). Accordingly, if DL can lead to positive effects on jumping, acceleration, and change of direction, DL could present as a more practical training exercise than that of BSQ.

This study aimed to compare the effects of DL and BSQ on jumping, acceleration, and change of direction.

Twenty-three men (12 in the DL group [age: 20.3 ± 1.4 years old, height: 169.6 ± 6.7 cm, body weight: 65.7 ± 11.2 kg] and 11 in the BSQ group [age: 20.2 ± 1.9 years old, height: 171.5 ± 4.8 cm, body weight: 70.1 ± 6.8 kg]) participated in this study. The participants performed five repetitions maximum (RM) of DL and BSQ, and the isokinetic strength of hip joint extension, muscle thickness of the gluteus maximus and hamstrings, countermovement jump (CMJ) height, 10 m sprint time, and T-test results were measured. The 1RM was estimated using the 5RM and normalized to body weight (BW). Both groups performed supervised DL and BSQ training for eight sessions.

There were significant improvements on 1RM DL/BW ( p < 0.01), 1RM BSQ/BW ( p < 0.01), and 10 m sprint ( p < 0.01) in the two groups. The effect sizes ( d ) of the DL and BSQ groups were 2.01 and 1.04 for 1RM DL/BW, 1.08 and 2.08 for 1RM BSQ/BW, 0.35 and 0.11 for CMJ height, and - 0.94 and - 0.54 for 10 m sprint, respectively.

DL training might improve jumping and acceleration compared to those of BSQ training.

Although squat depth determines the weight that can be lifted while squatting, it is unclear whether the one-repetition maximum (1RM) at one squat depth can be used to estimate the 1RM at another squat depth.

To determine the correlations between 1RM weights at different back squat (BSQ) depths in frequently trained male collegiate athletes.

This cross-sectional study included 26 male collegiate athletes. Body composition, lower extremity length, and 1RM of BSQ were measured. 1RM of BSQ was measured at three positions (quarter, half and parallel positions), defined as 45 degrees of knee flexion (quarter, Q-SQ), 90 degrees of knee flexion (half, H-SQ), and femur parallel to the ground (parallel, P-SQ), respectively. All testing was conducted by a certified strength and conditioning specialist. Pearson’s correlation analysis and Spearman’s rank correlation were used to examine the correlation between 1RM at each squat depth.

There was a significant correlation between 1RM in the H-SQ and P-SQ positions ( p < 0.001, r = 0.725, R 2 = 0.526, y = 1.0728 x + 24.641), but no significant correlation between 1RM of Q-SQ and P-SQ, and 1RM of Q-SQ and H-SQ. There were significant correlations between the 1RM/BW of Q-SQ and height ( p = 0.001, r = 0.594), and with the length of the lower extremities ( p = 0.002, r = 0.586).

Mutual estimation of the 1RM of H-SQ or P-SQ from the 1RM of the other squat position is possible. Estimation of the 1RM of Q-SQ from the 1RM of H-SQ or P-SQ is, however, difficult, and must be measured separately. Future studies should be conducted with larger sample sizes, in athletes of various sports, and in females.

Passive heating has attracted attention as a potentially promising recovery modality in sports. However, investigations of passive heating have yielded only inconsistent results for exercise performance.

To investigate the acute effects of local passive heating administered between repeated bouts of isokinetic exercise.

The experiment was a randomized crossover study. There was a total of three visits including a familiarization visit. During the remaining two visits, eleven healthy men performed three bouts of nine sets of isokinetic knee extensions using their dominant single-leg (30 repetitions/set, 180 ∘ /sec). A 15 min recovery, during which a local passive heating pad at control (CON) or heating (HT) was applied to the rectus femoris, was afforded after the 3rd and 6th sets (Recovery 1 and 2). Isokinetic exercise performance, as assessed by peak torque, total work, and average power was analyzed using two-way repeated-measures ANOVA.

Following Recovery 1 and 2, isokinetic exercise performance, as assessed by peak torque, total work, and average power was reduced in Set 4 ( p < 0.001, p < 0.001, p = 0.080) and Set 7 ( p < 0.001, p < 0.001, p = 0.009) in the HT group relative to the CON group. Electromyography analysis revealed that signal amplitude was lower in the HT group in Set 4 ( p < 0.001) subsequent to Recovery 1, and that firing frequency was higher in Set 7 ( p = 0.002) in the HT group after Recovery 2. Furthermore, EMG time-frequency maps from one representative participant showed that following Recovery 1 and 2 peak energy decreased during the first five repetitions in Set 4 and 7.

Local passive heating administered during recovery decreased subsequent performance of isokinetic knee extensors, muscle activation ability and increased firing frequency maintaining force output. Therefore, local passive heating is not an appropriate acute recovery strategy for isokinetic exercises.

It is unknown whether a session of isometric handgrip (IHG) exercise can influence the blood pressure of hypertensive and normotensive individuals.

To compare post exercise hypotension among groups with different resting blood pressure (BP) levels.

56 Malay male volunteers (12 normotensive, 14 pre-hypertensive, 19 hypertensive stage 1, and 11 hypertensive stage 2) completed four sets of 2-minute isometric handgrip exercises at 30% of their maximum handgrip contraction with a one-minute break between the sets. Systolic BP (SBP), diastolic BP (DBP), pulse pressure (PP), mean arterial pressure (MAP), resting heart rate (RHR), and handgrip strength (HGS) were measured before and after an hour of IHG exercise. A paired sample t -test, one-way ANOVA, and two-way repeated measure ANCOVA were used to examine the data.

All parameters, except RHR and PP, were significantly changed following the exercise across the BP groups. The SBP, MAP, and HGS were greatly reduced among hypertensive stage 1 (SBP = - 6.3 ± 0.6 mmHg; MAP = - 4.8 ± 1.1 mmHg; HGS = - 6.8 ± - 0.4 mmHg) compared to other groups. Meanwhile, the most DBP was reduced among hypertensive stage 2 (mean = - 5.2 ± 0.6 mmHg).

The current study discovered a significant reduction in BP among hypertensive stage 1 and 2 individuals after a session of IHG exercise.

Moderate-intensity interval training (MIIT) may be a viable exercise format for improving body composition, aerobic fitness, and health-related variables.

This randomized trial aimed to analyze the effect of MIIT or high-intensity interval training (HIIT) on aerobic fitness, body composition variables, and resting metabolic rate (RMR) in women with overweight or obesity.

31 sedentary adult women with overweight or obesity performed 7 weeks × 3 weekly sessions of either HIIT or MIIT. Physical and physiological tests were applied before and after training.

In both analyses (intention-to-treat and by adherence to the training), aerobic fitness showed a time effect ( p = 0.041 and p = 0.015), but without differences between groups ( p > 0.05). No group (HIIT vs. MIIT), time (pre vs. post), or interaction effects (group vs. time) were found for RMR, body composition markers (fat mass, body fat percentage, lean mass), or body mass index – BMI ( p > 0.05). In addition, MIIT induced a relatively high drop-out rate.

This study suggested that the short-term (7-weeks) interval exercise training was effective for increasing aerobic fitness, and moderate-intensity intervals were as effective as high-intensity intervals. However, neither training format was effective for changing RMR, body composition variables, or BMI of women with overweight or obesity. Clinical trial ID: RBR-9jd7b7.

Hamstring shortening altered joint reaction forces during activities of daily living (ADL), causing knee pain. Moreover, weak quadriceps may negatively distribute the compressive and shear forces at the knee joint.

The study examined the effect of adding hamstring stretching to quadriceps strengthening exercises on joint space narrowing (JSN), medial joint space width (mJSW), and physical abilities in patients with knee osteoarthritis (KOA).

A total of 42 osteoarthritis patients, aged from 50 to 65 years, were randomized and assigned into 2 groups: the study and the control groups. Quadriceps strengthening exercises were given to both groups, while static hamstring stretching was applied to only the study group. Patients of both groups were screened with a weight-bearing x-ray beam to investigate the JSN, mJSW, and functional abilities measured in the WOMAC scale. The Outcomes were evaluated at the baseline and immediately after 6 weeks of treatment.

The mJSW improved in the study group ( p < 0.001) compared to the control group ( p = 0.07). The OARSI JSN was enhanced significantly in both groups, but in favor of the study group ( p < 0.001) over the control group ( p = 0.046). Both MVIC and total score of WOMAC were significantly improved in both groups ( p < 0.001).

Adding static hamstring stretching to quadriceps strengthening exercises provided a substantial effect on mJSW, JSN, and functional abilities in KOA patients.

The effects of a long-term static stretching program on physical performance parameters have not been elucidated completely, although the effects on muscle flexibility have a consensus.

This study aimed to investigate the effect of a long-term static stretching program on physical performance and muscle properties.

Participants performed a 2-min static stretching for the ankle joint 5 times per week for 4 weeks. Physical performance and muscle properties was measured before and after the static stretching program.

Results showed that range of motion (ROM), dynamic postural stability, and muscle hardness were positively changed, whereas other variables i.e. maximal isometric plantar flexion moment, jump heights, muscle-tendon junction displacement and its angle, were not.

Four-week of SS program may improve ROM, dynamic postural stability, and muscle hardness without decreasing physical performance.