Search results for "Human physiology"

Ethnic differences in serum lipoproteins and their determinants in South African women

2010

Cognitive mechanisms underlying reading and spelling development in five European orthographies

2014

This paper addresses the question whether the cognitive underpinnings of reading and spelling are universal or language/orthography-specific. We analyzed concurrent predictions of phonological processing (awareness and memory) and rapid automatized naming (RAN) for literacy development in a

Muscle cross-sectional area, force production and relaxation characteristics in women at different ages

1991

Thirty women, divided among three different age groups, i.e. 30 years (range 26–35;n = 10), 50 years (range 46–55;n = 10) and 70 years (range 66–75;n = 10) volunteered as subjects for examination of the characteristics of the muscle cross-sectional area (CSA), maximal voluntary isometric force, isometric force-time and relaxation-time of their leg extensor muscles. The CSA of the quadriceps femoris muscle in the youngest age group was slightly larger (NS) than in the middle-aged group and much larger (P<0.41) than in the oldest age group whose CSA was markedly smaller (P<0.01) than the middle-aged group. Maximal force in the youngest group was slightly greater (NS) than in the middle-aged g…

Methodical aspects of perceived exertion rating and its relation to pedalling rate and rotating mass.

1975

Methodical aspects of the relationship between pedalling rate and rotating mass and perceived exertion rating (PER; Borg, 1962) were studied in trained, untrained, and ill subjects in bicycle ergometry. Pedalling rate varied between 40 and 100 rpm, work load steps were 5, 10, 15 and 20 mkp/sec in the healthy subjects, and 2.5, 5, 7.5 and 10 mkp/sec in the patients. PER decreased with increasing pedalling rate in all healthy subjects. In the patients, PER increased moderately at work load of 2.5 mkp/sec, but decreased at higher work loads up to 80 rpm, followed by a slight increase at 100 rpm. Higher mass of the flywheel, studied in 6 trained subjects, lowered the PER insignificantly. In the…

Dependence of motion sickness in automobiles on the direction of linear acceleration.

1982

Thirty-eight normal volunteers were tested in an ambulance car while being accelerated in one of the following positions: (1) sitting upright facing forward in the car, (2) lying supine on a stretcher head forward, (3) supine position head backward. Consecutive short periods of negative horizontal acceleration (0.7–0.95 g) were achieved by brisk braking manoeuvres of the car, followed by weak reacceleration (0.15 g). Motion sickness symptoms were observed and recorded after each experiment using a special motion sickness scaling index which was weighted according to the strength of any particular symptom. The results indicate that horizontal linear acceleration in a car, such as experienced…

Fitness and lean mass increases during combined training independent of loading order.

2014

Although the benefits of combined endurance (E) and strength (S) training for the development of physical fitness and health are well known, scientific examination of the effect of loading order when E and S are combined into the same training session (E+S vs S+E) is rare. This study investigated the effects of moderate frequency E+S versus S+E training on physical fitness, body composition, and blood lipids.Physically active and healthy young men performed E+S (n = 16) or S+E (n = 18) training 2-3 times a week for 24 wk. Endurance (by incremental bike test) and strength (by dynamic leg press) performance as well as body composition (by dual-energy x-ray absorptiometry), muscle cross-sectio…

The mechanical efficiency of locomotion in men and women with special emphasis on stretch-shortening cycle exercises.

1986

The mechanical efficiency of the leg extensor musculature of men and women was examined with a special "sledge ergometer". The subjects (ten males and ten females) performed pure positive work, pure negative work and a combination of negative and positive work (stretch-shortening cycle). The mechanical efficiency of pure positive work was on average 19.8 +/- 1.2% for female subjects and 17.4 +/- 1.2% for male subjects (t = 4.12, P less than 0.001), although the work intensity was equal in both groups. The mechanical efficiency of pure negative work was slightly lower in women than in men (59.3 +/- 14.4% vs 75.6 +/- 29.3%). The mechanical efficiency of positive work (eta +) in a stretch-shor…

The order effect of combined endurance and strength loadings on force and hormone responses: effects of prolonged training

2014

Purpose To examine acute responses and recovery of force and serum hormones to combined endurance and strength loadings utilizing different orders of exercises before and after training. Methods Physically active men were matched to an order sequence of endurance followed by strength (E + S, n = 12) or strength followed by endurance (S + E, n = 17). The subjects performed one experimental loading consisting of steady-state cycling and a leg press protocol before and after 24 weeks of order-specific combined training. Results No between-group difference in acute reductions of force was observed at week 0 (E + S −23 %, p < 0.001; S + E −22 %, p < 0.01) and 24 (E + S −25 %, p < 0.001; S + E −2…

Changes in corticospinal excitability during an acute bout of resistance exercise in the elbow flexors

2014

Purpose Hypertrophic resistance exercise (HRE) induces central and peripheral fatigue. However, more detailed information about changes in corticospinal excitability remains to be elucidated. Methods Eleven volunteers participated in the upper arm HRE which included one repetition maximum (1 RM) control contractions and three sets of 13 RM (SET1–3). Transcranial magnetic stimulation (TMS) was applied during maximal isometric voluntary contraction (MVC) at the end of each set and during control contractions to study changes in corticospinal excitability. Electrical stimulation was used in order to measure peripheral changes. Results MVC decreased after each set when compared to control contr…

Tracking the corticospinal responses to strength training

2020

Purpose\ud The motor cortex (M1) appears to be a primary site of adaptation following both a single session, and repeated strength-training sessions across multiple weeks. Given that a single session of strength-training is sufficient to induce modification at the level of the M1 and corticospinal tract, this study sought to determine how these acute changes in M1 and corticospinal tract might accumulate across the course of a 2-week heavy-load strength-training program.\ud \ud Methods\ud Transcranial magnetic stimulation (TMS) was used to infer corticospinal excitability (CSE), intracortical facilitation (ICF), short and long-interval intracortical inhibition (SICI and LICI) and silent per…