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Muscle fatigue is known to be associated with a deteriorated muscle coordination and impaired movement performance in variety of voluntary movements. The aim of this study was to investigate the generally underexplored effect of muscle fatigue on both the coordination between grip force (GF; the force component perpendicular to the hand–object contact area that provides friction) and load force (LF; the parallel force component that can move the object or support the body) as well as movement performance in manipulation tasks. Fifteen participants performed a variety of static and dynamic manipulations both with and without a preceding procedure designed to fatigue the arm and hand muscles. The tasks involved exertion of ramp-and-hold and oscillation patterns of LF against an externally fixed instrumented device, and a simple lift of a freely moving device. The results revealed a fatigue-associated decrease in GF scaling (i.e., the magnitude of GF relative to LF) and GF–LF coupling (correlation between GF and LF), while the task performance regarding the accuracy of exertion of the prescribed LF profiles remained unaffected. We conclude that muscle fatigue both partly decouples GF from LF and reduces the overall GF magnitude, which could potentially explain why hand-held objects are more likely to drop when manipulated with fatigued muscles. However, the unaffected task performance could be explained either by the relatively low level of muscle forces required by the tested tasks, the moderate level of the fatigue imposed, or both.

We tested the hypotheses that the individual strength properties depend on the applied test and the variable extracted, rather than on the muscle group tested. Flexor and extensor muscles acting in the knee and elbow joint were tested in 58 participants. The standard strength test (SST; based on sustained maximum contraction) and alternating consecutive maximum contractions (ACMCs; alternating contractions of antagonistic muscles) performed under static conditions were separately applied to provide the maximum force (F) and the rate of force development (RFD) of each tested muscle. The principal component analysis applied on all 16 variables revealed three factors that explained 85.5% of the total variance. Contrary to our hypotheses, the individual factors were loaded with the variables recorded from individual muscles, rather than with either the particular variables or tests. The present findings suggest that recording both F and RFD in routine strength testing procedures could be redundant since they may assess the same strength property of the tested muscle. In addition, ACMC may be a feasible alternative to SST since it could assess the same strength properties from two antagonist muscles through a single trial, while being based on relatively low and transient forces.

Aerobic fitness, endurance, and cardiovascular endurance are synonyms for work capacity, which itself is an important prerequisite for the health and life of every man. The purpose of this research was to identify the trend of aerobic fitness of students in the last 15 years. The Survey method, which implies nonexperimental crossectional research, was used. The instrument is UKK 2km, walking test. The total sample consisted of 605 subjects (389 males, 216 females), students of Faculty of Sport and Physical Education, aged 18-28 years. They were divided into three groups, according to when they were tested, the first group was tested in the period 1997-2000 (N = 299), the other was tested from 2001-2004 (N = 200), the third was tested in 2012 (N = 106). Analysis of the results showed a decreasing trend in fitness index of male students with 104.1 to 77.3, and of the female students from 96.4 to 84.8. T-tests confirmed differences in fitness index, at the level of p

The aim of this study was to defi ne the actual model of body composition status of working age women in the territory of Belgrade. The sample comprised 109 women respondents, of an average age of 35.2±9.5 and the length of service = 9.6±9.3 years. All measurements were performed in the period from 2011–2012 in the Teaching -research laboratory of the Faculty of Sport and Physical Education of the University of Belgrade, by applying stadardised procedure of electrical multichannel bioimpedance method. The researched encompassed twenty-two (22) variables – fourteen basic (14) and eight (8) derived (index) variables. Basic variables were: BH – body height, BM – body mass, ICF – intracellular fl uid, ECW – extracellular fl uid, TBW – total body fl uids, Proteins, Minerals, BMC (Osseous) – bone mineral contents, BFM – total body fat mass, SMM – skeletal muscle mass, VFA – visceral fat area, BCM – body cell mass, BMR – basal metabolic rate, FIS – fi tness score as assessment of body composition. The derived (index) variables were: BMI – body mass index, PBF% - percent of body fat, PBW - percent of body water, PFI - protein fat index, PSMM – percent of skeletal muscle mass, SMMD – skeletal muscle mass density, OBMi – Osseous-body mass index, PBMi – protein body mass index. The results showed that the average body mass of the respondents was 67.66±13.39 kg, body height 167.04±6.62 cm, body mass index 24.27±4.66 kg/m2, muscle mass 26.55±4.46 kg, muscle mass percentage 29.09±8.47, body fat mass 20.52±9.74 kg, body fat percentage 29.09±8.47, visceral fat area was 77.92±40.23 cm2 and fi tness score 73.23±6.75 of index points. The obtained results led to the conclusion that the current morphological status of the studied women partially corresponds to a type of normal weight. BMI and the representation of body fat had nearly limiting values towards obesity. A very high percentage of women was recorded in the category of pre-obese and obese according to BMI (40%) and PSMM (36%). Based on the results of this study, it can be claimed that the four-dimensional model (4D model) of body composition of working-age women from the measured sample has the following characteristics: in women of average body mass of 67.66 kg – water content is 34.58 L or 51.11%, protein mass is 9.25 kg or 13.68%, mineral mass is 3.30 kg or 4.88% and fat mass is 20.25 kg or 30.32%.