A strength-endurance index for power grip

Grip Strength-Endurance in Ambitious and Recreational Climbers: Does the Strength Decrement Index Serve as a Feasible Measure?

The present study investigated the time course of repetitive maximal isometric grip strength, depending on the arm position, laterality (dominant vs. non-dominant side), and climbing level. The intervention aimed to provide a feasible indicator of maximal strength-endurance in climbing. Seventeen recreational (climbing level (CL): 6.8 (SD 0.5) on the Union Internationale des Associations d’Alpinisme (UIAA) metric scale) and eleven ambitious (CL: 8.7 (SD 0.6) UIAA metric scale) climbers (age: 27 (8) years; BMI: 21.6 (1.9) kg/m²; ape index (arm span divided by body height): 1.05 (0.18); training volume: 2.2 (1.0) h/week). Participants completed maximal isometric handgrip strength (F_max) tests in four positions (left and right hand beside the trunk as well as left and right hand above the shoulder) plus twelve repetitive work-relief cycles, lasting 4 and 1 s where isometric strength, heart rate, and perceived exertion were recorded. F_max differed between groups in nearly all positions. A large side × position × time × group interaction was observed for repetitive isometric grip strength (p = 0.009, η_p² = 0.71). However, subsequent post-hoc tests did not reveal a significant difference between groups during each testing position. Additional correlation analysis between asymmetry and CL showed an inverse relationship for ambitious climbers (r = −0.71). In conclusion, the degree of grip strength decline did not relevantly differentiate between ambitious and recreational climbers. Thus, the time course of handgrip strength seems to mainly rely on maximal grip strength during the first contraction.

The effect of motivational interviewing-based intervention using self-determination theory on promotion of physical activity among women in reproductive age: A randomized clinical trial

Background

Physical activity (PA) prevents chronic diseases. Self-determination theory (SDT) provides a useful framework to understand the nature of motivational interviewing (MI).

Objective

This study aimed to determine the effect of MI-based intervention using SDT on the promotion of PA among women in reproductive age.

Methods

Seventy women in reproductive age were selected by clustering sampling method for this randomized controlled trial. The questionnaire included the variables of physical fitness test, SDT, and global physical activity questionnaire (GPAQ). The validity of the questionnaires was approved using content validity ratio (CVR) and index (CVI). The reliability and internal consistency of the questionnaires and measures was approved using test-retest method and Cronbach’s alpha test, respectively. The intervention group (n=35) received four MI sessions through theory and one standard education session about PA. The control group (n=35) received a standard education session about PA.

Results

Four months after the intervention, an increase in the mean scores of total PA (p<0.001, ES=4.77), physical fitness tests including flexibility (p<0.001, ES=1.59), muscular endurance (p<0.001, ES=2.0), cardiorespiratory endurance (p<0.001, ES=0.51), and a decrease in mean scores of agility test (p<0.001, ES= − 0.51) and sedentary behavior (p<0.01, ES=− 0.74) was observed in the intervention group compared to the control group. The intervention group reported an increase in the scores of intrinsic motivation (p<0.001, ES=3.34), identified regulation (p<0.001, ES= 1.28), perceptions of competence (p<0.001, ES=0.81) and autonomy (p<0.001, ES=2.01), enjoyment (p<0.001, ES=0.98) and health motives (p<0.01, ES=0.19), health care climate (p<0.001, ES=4.6), and a decreased score of external regulation (p<0.01, ES=−0.55) and amotivation (p<0.01, ES= −0.56) over time, compared to the control group.

Conclusion

MI-based intervention using SDT was effective on the promotion of PA.

Trial registration

The Trial was registered at the Iranian Registry of Clinical Trial (http://www.irct.ir) with the Irct ID: IRCT2015101924592N1.

The Effect of Wrist Position on Grip Endurance and Grip Strength

PURPOSE

Studies on grip endurance are scant even though it is an important topic with practical implications. This study compares the effect of wrist position, in the flexion-extension plane, on grip endurance and grip strength.

METHODS

Grip strength and grip endurance were quantified bilaterally at 6 different wrist positions (unrestrained, 45°, 30°, and 15° extension, 0° and 30° flexion) in 38 healthy right-handed individuals.

RESULTS

Our results show that wrist orthosis significantly reduced grip strength across all positions and the maximum grip strength in the position with an orthosis occurred at 15° and 30° extension for the dominant hand and 15°, 30°, and 45° extension for the nondominant hand. Hand dominance and sex did not significantly affect grip endurance. Using a wrist orthosis did not significantly reduce grip endurance at 45° and 30° extension.

CONCLUSIONS

At a position of 30° of wrist extension, maximal grip strength is achieved without significantly compromising grip endurance. This has clinical implications for decisions regarding the optimal position for orthosis and radiocarpal joint arthrodesis.

CLINICAL RELEVANCE

This study would aid both surgeons and therapists in facilitating discussion with patients regarding the various therapeutic options in managing wrist pathologies.

Tracking upper limbs fatigue by means of electronic dynamometry

This study aimed to identify useful electronic grip dynamometry parameters to track differences between trained (TR) and untrained (UT) participants, and between dominant (DO) and non-dominant (ND) limbs as a consequence of upper limbs muscle fatigue following 10 RM tests of the brachial biceps. This experimental study with transversal design involved 18 young adult males, of whom 9 were untrained and 9 were experienced in resistance training.Isometric grip force was evaluated (30 seconds long) previous and after 10RM tests by means of a G200 Model grip dynamometer with precision load cell (Biometrics(r)). Significant differences between initial and final measurements were found only for trained participants: Peak force for TR-DO (67.1 vs 55.5 kgf, p = .0277); Raw average for TR-DO (46.96 vs 42.22 kgf, p = .0464), and for TR-ND (40.34 vs 36.13 kgf, p = .0277). Electronic grip dynamometry efficiently identified upper limbs fatigue in trained participants, being raw average measurements the best parameter.