Isokinetics and Exercise Science

Grip and knee strength are commonly measured but controversy exists as to whether either is a proxy for the other. The purpose of this meta-analysis was to summarize the correlation between the 2 variables.

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

Results from 17 studies were consolidated. The summary correlation between grip and knee extension strength was 0.64 with 95% CI of 0.57 to 0.71. Data were highly heterogeneous but did not show publication bias.

The correlation between the grip and knee extension strength is good. However, it is not good enough to justify using either as a proxy for the other.

The ability of the lower-extremity muscle activation directly affects the performance and in turn interacts with the loading conditions of the muscle itself. However, systematic information concerning the characteristics of lower-extremity muscle during landings is lacking. In particular, the landing height and shoes are also important factors based on the actual situation, which could further contribute to understanding the neuromuscular activity and how biochemical response of the body tissues to double-leg drop landings.

The study was to investigate the effects of landing tasks on the activation of lower-extremity muscles and explore the relationship among movement control, landing heights, shoe cushioning, and muscle activities.

Twelve male basketball players were recruited to perform drop jump (DJ) and passive landing (PL) from three heights (30, 45, and 60 cm) while wearing highly-cushioned basketball shoes (HC) and less-cushioned control shoes (LC). EMG electrodes were used to record the activities of the target muscles (rectus femoris, vastus lateralis, biceps femoris, tibialis anterior, and lateral gastrocnemius) during the landing tasks.

Pre- and post-activation activity of the lower-extremity muscles significantly decreased during PL compared with those during DJ ( p < 0.05). No significant shoe effects on the characteristics of muscle activation and coactivation during DJ movements were observed. However, the participants wearing LC showed significantly higher muscle post-activation ( p < 0.05) at the three drop heights during PL compared with those wearing HC. Coactivation of the ankle muscles was higher in LC than in HC during 30-cm PL ( p < 0.05).

The activation patterns of lower-extremity muscles can be significantly influenced by landing types. Highly-cushioned basketball shoes would help reduce the risk of injuries by appropriately tuning the muscles during the PL.

Reduced mobility of upper and lower limbs has been associated with injuries in athletes. The Combined Elevation Test (CET) and the Weight-Bearing Dorsiflexion Lunge Test (WBDLT) are frequently used in clinical and research settings in face-to-face evaluations. However, some situations require physical distancing, and it is unknown whether those tests via telehealth are reliable.

To evaluate the intra-rater reliability, the Standard Error of Measurement (SEM), and the Minimum Detectable Change (MDC) for considering a real change on the CET and WBDLT were calculated for healthy athletes via telehealth.

67 athletes (25 years, 73 kg, and 1.75 m on average) participated in this study. 37 athletes performed the CET and 50 performed the WBDLT (20 performed both tests). Reliability was assessed through two online evaluations (7 to 15-days apart).

ICC 3 , 3 ranged from 0.88–0.97 for the CET and from 0.95–0.98 for the WBDLT. For both tests, SEM values were low ( < 8.9%) and the MDC 90 was approximately 4 cm and 2 cm for the CET and WBDLT, respectively.

Telehealth-based findings relating to CET and WBDLT are reliable in healthy adult athletes and can be used to screen this population when face-to-face evaluations are not feasible.

Trunk muscle activity during isometric exercise is altered by external-focus instruction.

To check alterations in trunk muscle activity during side plank exercise both with and without instructions to refrain from crushing an item (external-focus instruction method).

Twenty-one healthy men aged 20–49 participated in this study. Ten trunk muscle activities were measured using surface electromyography during side plank exercises both with and without external-focus instruction. The unpaired t-test or Mann–Whitney U test was used to compare differences between exercise tasks and between sides.

Side plank exercise with external-focus instruction increased activity of the upper trapezius, lower trapezius, latissimus dorsi, medial head of the triceps, and internal oblique on the supported side when compared with that without external-focus instruction ( p < 0.05 for all). On the unsupported side, side plank exercise with external-focus instruction significantly increased activity of the upper trapezius, lower trapezius, latissimus dorsi, medial head of the triceps, clavicular part of the pectoralis major serratus anterior, external oblique, rectus abdominis, internal oblique, and multifidus when compared with that without external-focus instruction ( p < 0.001 for all).

Adding the external-focus instruction method to the conventional side plank exercise may be effective in increasing the trunk muscles’ activity.

Most previous studies have focused on increasing hamstring flexibility when knee extension range of motion (KE ROM) is restricted. However, it was demonstrated that the tensile force generated in the upper body could be transmitted to the contralateral lower extremity.

This study examined the effect of novel diagonal stretching combining trunk rotation and trunk flexion on the contralateral KE ROM.

Two different positions (sitting with a neutral pelvis position and sitting with trunk rotation) were randomly selected and the contralateral and ipsilateral KE ROM was measured in each position. As for the stretching intervention, trunk rotation and slight trunk flexion were applied in sitting with a neutral pelvic position.

On the contralateral side, KE ROM was significantly different in all pairwise comparisons ( p < 0.001). On the ipsilateral side, a significant difference in KE ROM was only observed between measurements taken after stretching compared to measurements taken during trunk rotation ( p = 0.005).

The tensile force in the upper body significantly affects tissue extensibility in the lower extremity in the contralateral side, leading to the restriction of active maximum knee extension. Diagonal stretching techniques may successfully enhance mobility in the contralateral leg.

Vertical jump is an index representing leg power. It is important to determine factors that influence the vertical jump to help athletes improve their leg power.

This study aimed to determine the relationship between lower limbs muscle volume and peak vertical jump (VJ) power in children for both sexes.

Fourty children healthy boys ( n = 20) and girls ( n = 20) aged 10 to 12 years old, randomly performed three VJ modalities: squat jump (SJ), counter movement jump without (CMJ) and with arm swings (CMJarms). Lower limbs muscle volume (MV) estimated using a standard anthropometric method. Peak power (PP) calculated by Sayers equation.

significant correlations between MV and Peak vertical jump power showed for both sexes. Likewise, significant correlations were found between MV and body mass for boys ( r = 0.66; p = 0.001) and for girls ( r = 0.59; p = 0.006).

The correlation observed between peak vertical jump power and MV in both sexes can be considered as estimation tool of the lower limbs muscle power. Lower limb’s muscle volume are determining factor in muscle power for both sexes.

The World Health Organization (WHO) uses the International Classification of Functioning, Disability, and Health (ICF) model to provide physical therapy diagnoses and interventions. However, the relationship between clinical assessment and imaging remains unclear.

This study aimed to determine the relationships between body function/structure, activity, and participation outcomes following neurorehabilitation in children with cerebral palsy (CP).

Nineteen children (9 girls mean age 8.8 ± 1.8 years) with CP participated in this study. Clinical motor function tests included the quality of upper extremity skills test (QUEST), Wolf motor function test (WMFT), Functional Independence Measure for Children (WeeFIM), and the Jebsen-Taylor Hand Function Test (JTHFT). Ultrasound imaging was used to measure muscle thickness, which characterizes the body structure, and activity domain variables.

The correlations between body structure domain (muscle thickness), activity domain (QUEST, WMFT, WeeFIM) and participants variable (JTHFT) were significant, ranging from r = - 0.484 to 0.893, P < 0.05.

These novel findings suggest that muscle thickness ultrasound imaging is closely associated with WMFT, WeeFIM, and QUEST variables. This finding provides important clinical insights when using broad clinical assessment and imaging in children with CP.

Dynamic stretching (DS) and ballistic stretching (BS) are similar stretching methods, but the differences between them are unclear.

To examine the immediate effects of unilateral hamstring DS and BS on straight leg raise (SLR), knee flexion range of motion (KF-ROM), and KF and knee extension maximal isokinetic peak torque (KF-MIPT and KE-MIPT) of the bilateral limbs.

Twelve healthy adult men performed four sets of 2 min each of non-stretching, DS, or BS of the right lower extremity. Bilateral SLR, KF-ROM, KF-MIPT, and KE-MIPT were measured pre- and post-intervention; a three-way (intervention × limb × time) repeated-measures analysis of variance (ANOVA) was used.

The SLR of the stretched limb ( p < 0.01) was higher with DS than that pre-intervention. SLR ( p < 0.01) and KF-ROM ( p < 0.05) of the stretched limb and SLR ( p < 0.05) and KF-ROM ( p < 0.05) of the contralateral limb were higher with BS than those pre-intervention. There was no significant main effect or interaction between KF-MIPT and KE-MIPT.

DS and BS had slightly different effects on ROM, and neither affected muscle strength; thus, combining the techniques during warm-up might be helpful.

Stretching is commonly used for clinical and sports reason but the effects vary on time and the technique used.

To determine the acute effects of static and dynamic stretching of gastrocnemius muscle on muscle-tendon unit (MTU) and dorsiflexion range of motion (ROM) in the same individuals; to find out how long the stretching effects endure.

Twenty-eight males (mean age: 22.18 ± 2.58 years) were included in the study. A 45-s static stretching (SS) exercise was applied to the right leg 5 times and dynamic stretching (DS) of same duration to the other leg. Change in MTU was assessed by ultrasonography and active and passive ROM was measured with goniometer. All evaluations were performed before, immediately following, 5-min, 15-min and 30-min after stretching.

Muscle thickness and pennation angle did not change over time with either techniques ( p > 0.05). A significant muscle-tendon junction (MTJ) displacement occurred after the techniques ( p < 0.05); the highest change was achieved after DS ( p < 0.05). Both techniques improved active ROM values similarly ( p < 0.05), but only dynamic stretching increased passive ROM significantly ( p < 0.05). Active and passive ROM and MTJ displacement values at 30 th – min were still higher than the baseline ones on the DS side ( p < 0.05). However, SS increased active ROM angle immediately after application but this increment declined until the final measurement.

We recommend using the dynamic stretching technique to achieve greater and longer lasting increases in tendon length and range of motion.