.40 (0.02) 3.46 (0.04) Women futsal players First division (n = 28) 6.63 (0.46) 7.64 (0.40) 12.6 (1.2) −0.870 (0.068) −8.09 (0.70) 42.5 (3.4) 1.49 (0.05) 3.77 (0.13) Abbreviations: DRF, decrease in the ratio of horizontal to resultant force; F 0 , theoretical maximal force; F–V slope, slope of the force
Pedro Jiménez-Reyes, Amador García-Ramos, Victor Cuadrado-Peñafiel, Juan A. Párraga-Montilla, José A. Morcillo-Losa, Pierre Samozino and Jean-Benoît Morin
Jonathan C. Reid, Rebecca M. Greene, Nehara Herat, Daniel D. Hodgson, Israel Halperin and David G. Behm
Contrary to adult force reserve strategies, it is not known whether adolescent females with less experience performing maximal voluntary contractions (MVC) have specific responses to a known or unknown fatigue endpoint.
Using a counterbalanced random crossover design, fourteen inexperienced female adolescents completed three elbow flexor (EF) fatiguing protocols. Participants were randomly assigned to a control (informed they would perform 12 MVCs), unknown (not informed of the number of MVCs to be completed, but stopped after 12) or deception condition (instructed to complete 6 MVCs, however, after the sixth repetition performed another 6 MVCs). Before and during the interventions, EF impulse, force, and biceps brachii (BB) and triceps brachii (TB) electromyography (EMG) activity were recorded. Results: Participants exhibited decreases in impulse (10.9%; p < .05), force (7.5%; p = .001), BB (16.2%; p < .05) and TB (12.9%; p < .05) EMG activity between the pretest and the first repetition of all protocols. Knowledge of endpoint, or lack of it, did not change measures with the repeated MVCs. When informed about the final repetition, force remained depressed suggesting no physiological reserve.
Adolescent females exhibited an anticipatory response to the task of performing repeated MVCs. A lack of change with knowledge of endpoint indicates that those lacking in MVC experience do not employ the same pacing strategies as in previous studies of participants with MVC experience.
Han C.G. Kemper, G. Bertheke Post and Jos W.R. Twisk
This longitudinal study evaluates the relationship of food intake and physical activity with biological maturation of 200 boys and girls during adolescence and young adulthood. The subjects were followed during 9 years from ages 12 to 22 years, with repeated measurements at ages 13, 14, 15, 16, and 21. Biological maturation was estimated four times between ages 12 and 17 as skeletal age by radiographs of the left hand and wrist. Daily nutritional intake (macro- and micronutrients) was assessed with a cross-checked dietary history method. Daily physical activity was assessed through structured interview, whereby average weekly time spent in activity was used to assign a weighted activity score. The 107 girls and 93 boys were divided into three maturity groups: early maturers, late maturers, and average maturers. It was concluded that in both sexes, late maturation seemed to coincide with a higher energetic food intake and a slightly higher activity pattern than early maturation during adolescence.
Nicolas Berryman, Iñigo Mujika, Denis Arvisais, Marie Roubeix, Carl Binet and Laurent Bosquet
following moderators: strength-training intensity (maximal force, maximal power, submaximal force, combination), strength-training frequency (1 session/wk, 2 sessions/wk, ≥3 sessions/wk), duration of strength-training intervention (<24 sessions and ≥24 sessions), performance level (international, national
Daniel E. Lidstone, Justin A. Stewart, Reed Gurchiek, Alan R. Needle, Herman van Werkhoven and Jeffrey M. McBride
prolonged load carriage may therefore result in changes in muscle architecture. Increased fascicle lengths following repetitive fatiguing contractions has been shown to be related to reductions in maximal force. 17 The combined effects of heavy loads carried by soldiers and repetitive eccentric loading
Juan A. Escobar Álvarez, Juan P. Fuentes García, Filipe A. Da Conceição and Pedro Jiménez-Reyes
enhance jump performance while reducing the actual F-V IMB . 15 – 17 The actual and the optimal F-V profile can be computed during a series of loaded vertical jumps. 20 – 24 This field method provides the information related to theoretical maximal force ( F 0 ), theoretical maximal velocity ( V 0
Danny M. Pincivero, Rachael R. Polen and Brittany N. Byrd
the adjusted length of the resistance adapter for each participant, the averaged isokinetic maximal force applied against the point of contact (ie, the handgrip) was computed by dividing the sampled torque (N·m) by the measured adapter length. The length of the adapter was measured from the point of
Panagiotis Ioakimidis, Vasilios Gerodimos, Eleftherios Kellis and Spiros Kellis
Fifteen young basketball players (aged 14.4 – 0.5 yrs) underwent two identical testing sessions spaced one week apart, to determine the reliability of maximum isometric force and force-time parameters during a maximal bilateral isometric leg press effort. The maximal isometric force (MIF), the ratio of maximal force to time (T MIF) to attain maximal force (ARMIF), starting strength (F 50), and on a relative scale the time taken to increase the force from 10% to 30%, 60%, and 90% of maximal force were calculated. High intraclass correlation coefficients (ICC) were found for MIF (0.96), ARMIF (0.85), and F50 (0.90). On the relative scale, the ICCs for the times to produce 30%, 60%, and 90% of maximum force were 0.94, 0.95, 0.95, respectively. The present results indicate that maximum isometric force and the force-time parameters during a bilateral leg press can be measured reliably in pubertal basketball players.
Aïna Chalabaev, Jeanick Brisswalter, Rémi Radel, Stephen A. Coombes, Christopher Easthope and Corentin Clément-Guillotin
Previous evidence shows that stereotype threat impairs complex motor skills through increased conscious monitoring of task performance. Given that one-step motor skills may not be susceptible to these processes, we examined whether performance on a simple strength task may be reduced under stereotype threat. Forty females and males performed maximum voluntary contractions under stereotypical or nullified-stereotype conditions. Results showed that the velocity of force production within the first milliseconds of the contraction decreased in females when the negative stereotype was induced, whereas maximal force did not change. In males, the stereotype induction only increased maximal force. These findings suggest that stereotype threat may impair motor skills in the absence of explicit monitoring processes, by influencing the planning stage of force production.
Karin Tammik, Mariann Matlep, Jaan Ereline, Helena Gapeyeva and Mati Pääsuke
Isometric voluntary force production and relaxation capacity of the quadriceps femoris (QF) muscle was compared between 12 children with spastic diplegic cerebral palsy (CP) and healthy controls, age 10–11 years. Children with CP had less (p < .05) maximal voluntary-contraction force, voluntary activation, and rate of force development than controls. Visual reaction to contraction did not differ significantly in measured groups, whereas the reaction time to relaxation and halfrelaxation time were longer (p < .05) in children with CP. The authors concluded that in children with CP, the capacity for rapid voluntary force production and relaxation is reduced to a greater extent than isometric maximal force.