Browse

141 - 150 of 1,493 items :

  • Physical and Rehabilitation Medicine x
Clear All
Effect of Different Feedback Modalities on Swimming Pace: Which Feedback Modality is Most Effective?

Abstract

To compare the effect of three different feedback modalities on swimming pace, sixteen male swimmers and triathletes participated in this study. Each participant swam 3 x 400 m, one for each feedback modality, swimming front crawl at 80% of their individual swimming critical speed. Three feedback modalities were examined: self-pacing, real time visual feedback and real time voice feedback. The swimmers adopted a fast start in all feedback modalities. In the real time voice feedback modality, the data recorded during the second lap (200 m) showed a significant improvement of their swimming pace approaching the swimming pace intended (-1.47 s, p < .01, medium effect size 0.79). A significant improvement toward the swimming pace intended was also noticed at the third split time (300 m) (0.05 s, p < .01, large effect size 0.81) and at the fourth split time (400 m) (0.46 s, p < .01, medium effect size 0.76). In self-pacing, the swimmers were not able to swim in line with the swimming pace intended. In real time visual feedback modality, the swimmers did not show a significant improvement approaching the swimming pace intended. The results revealed that communication with the swimmers using the real time voice feedback induced a significant improvement in their swimming pace and could help the athletes to swim with accurate and consistent pace.

Open access
The Effect of Physical And Mental Stress on the Heart Rate, Cortisol and Lactate Concentrations in Rock Climbers

Abstract

Rock climbing is a physical activity that not only causes an increase in muscle tension, heart rate and blood pressure, but also results in the elevation of stress hormones including cortisol. It has not been established which of the above mentioned variables serve as the most accurate indicator of rock climbing-induced physical and mental stress. The aim of this study was to evaluate the effect of physical activity, short-term fatigue and mental demand on heart rate (HR), salivary cortisol (C) and blood plasma lactate (LA) concentrations in rock climbers under laboratory conditions. Twelve male and female rock climbers of comparable climbing performance (5a – 6b OS) were recruited. The participants completed two routes of different climbing difficulty (effect of physical demand), repeated a difficult route with a short 5-min recovery period three times (effect of fatigue), and repeated a difficult lead climb (effect of mental demand). Heart rate as well as C and LA concentrations were determined. The results indicated that more difficult climbing routes elicited increases in HR (especially relative values) and LA concentrations, whereas fatigue accumulation had an effect on climbing HR and relative C concentration values. Lead climbing only caused an increase in climbing HR. Based on the results it was concluded that HR was a good indicator of physical and mental stress intensity. Performing the same difficult route three times with a short recovery period in-between turned out to be the most demanding task and resulted in the highest increase of the cortisol concentration. Dynamics of changes in lactate concentrations depend on muscle loading (local muscular effort), lactate clearance and technical/tactical skills of the climber.

Open access
Effects of Core Strength Training Using Stable and Unstable Surfaces on Physical Fitness and Functional Performance in Professional Female Futsal Players

Abstract

The aim of this study was to assess the effect of core strength training performed on a stable surface (CTS) compared with core strength training performed on an unstable surface (CTU) on physical fitness (jump performance, sprint, and repeated sprint ability (RSA)) and quality of movement (Fundamental Movement Screen) in professional female futsal players. Fourteen professional female futsal players (mean age: 23.7 ± 5.1 years, age range: 18-28 years) were randomly assigned to a CTS (n = 7) or a CTU (n = 7) group. The intervention program was carried out 3 times a week over 6 weeks. Players of both groups performed the same four core-strengthening exercises. The only difference between the two interventions was that the CTU group performed all exercises (i.e., shoulder bridge, side bridge, prone plank, and crunch) on an unstable surface (Togu® Dyn-Air). Within-group analysis showed significant improvements (p < 0.001) in 10 m sprint performance from the pre- to post-test in the CTS (+4.37%) and CTU (+5.00%) groups. Players in both the CTS (+10.39%) and CTU (+11.10%) group also showed significant enhancement in the Functional Movement Screen total score, from the pre-test to post-test. In addition, a significant time effect was also observed for the CTU group in the relative score of the RSA test decreasing from the pre- to post-test (-30.85%). In the between-groups analysis, there were no significant differences between the core strength training groups (CTS vs CTU) in any variable. To conclude, sprint and Functional Movement Screen performance improved following CTS and CTU when conducted in combination with regular futsal training. In addition, CTU had limited benefit in RSA compared to CTS.

Open access
Effects of the Pitch Surface on Displacement of Youth Players During Soccer Match-Play

Abstract

The aim of this study was to analyze the effect of different pitch surfaces (artificial turf, natural turf and dirt field) on positioning and displacement of young soccer players (age: 13.4 ± 0.5 yrs; body height: 161.82 ± 7.52 cm; body mass: 50.79 ± 7.22 kg and playing experience: 3.5 ± 1.4 yrs). Data were collected using GPS units which allowed to calculate spatial distribution variability, assessed by measuring entropy of individual distribution maps (ShannEn). Ellipsoidal areas (m2) representing players’ displacement on the pitch, centred on the average players’ positional coordinates, were also calculated, with axes corresponding to the standard deviations of the displacement in the longitudinal and lateral directions. Analysis of variance (ANOVA) was used to evaluate differences between pitch surfaces and across players’ positions. There was significant effect in positioning (η2 = 0.146; p < 0.001) and displacement (η2 = 0.063; p < 0.05) by the players between pitch surfaces. A dirt field condition induced an increase in the players’ movement variability, while players’ displacement was more restricted when playing on artificial turf. Also, there were significant effects on positioning (η2 = 0.496; p < 0.001) and displacement (η2 = 0.339; p < 0.001) across players’ positions. Central midfielders presented the greatest movement variability and displacement while fullbacks showed the lowest variability. Subsequently, the results may contribute to implement strategies that optimise players’ performance in different surface conditions.

Open access
Exercise‐Based Cardiac Rehabilitation with and without Neuromuscular Electrical Stimulation and its Effect on Exercise Tolerance and Life Quality of Persons with Chronic Heart Failure

Abstract

The study compares the effect of an exercise-based cardiac rehabilitation program with a program combining physical exercise and lower extremity neuromuscular electrical stimulation (NMES) on the recovery of patients with chronic heart failure (CHF) with NYHA II-III symptoms. Seventy two patients with stable CHF were randomly distributed to four groups that received exercise-based cardiac rehabilitation and pharmacological treatment. Groups I and II were additionally administered NMES (35 Hz and 10 Hz, respectively) and in Group III sham NMES was applied. Group IV (controls) received solely pharmacological and exercise treatment. Exercise tolerance and quality of life were assessed in patients pre-treatment and at week 3. Three weeks of rehabilitation induced significant increases (p < 0.05) in the distance covered in the 6-minute walk test, the metabolic equivalent (MET), the duration of the treadmill exercise stress test, the left ventricle ejection fraction (LVEF) and improved quality of life in all groups, but between-group differences were not significant (p > 0.05). In none of the groups were the left ventricle end-systolic and end-diastolic diameters (mm) measured at week 3 significantly different from their baseline values (p > 0.05). Exercise-based cardiac rehabilitation contributed to higher exercise tolerance, LVEF and quality of life of CHF patients (NYHA II-III), contrary to cardiac rehabilitation combined with lower extremity NMES (35 Hz and 10 Hz) that failed to induce such improvements. More research is necessary to assess the therapeutic efficacy of NMES applied to CHF patients with NYHA IV symptoms.

Open access
The Influence of Verbal Instruction on Measurement Reliability and Explosive Neuromuscular Performance of the Knee Extensors

Abstract

The current study aimed to examine the effect of verbal instruction on explosive force production and between-session measurement reliability during maximal voluntary contractions of knee extensors. Following familiarization, 20 healthy males performed 3 maximal contractions with a “hard-and-fast” instruction and 3 maximal contractions with a “fast” instruction during 2 test-retest sessions. Knee extension maximal voluntary force (Fmax) and the maximal rate of force development (RFDmax) were measured. Maximal electromechanical delay (EMDmax), and the maximal rate of muscle activation (RMAmax) of quadriceps muscles were determined. No significant effect of instruction was observed on Fmax (p > 0.05). The RFDmax and RMAmax were significantly higher with the “fast” compared to the “hard-and-fast” instruction (36.07%, ES = 1.99 and 37.24%, ES = 0.92, respectively), whereas EMDmax was significantly lower with the “fast” instruction compared to the “hard-and-fast” instruction (-3.79%, ES = - 0.29). No significant differences between test and retest measurements were found (p < 0.05). However, the reliability of the RFDmax was higher with the fast instruction compared to the hard-and-fast instruction (CV: 7.3 vs. 16.2%; ICC: 0.84 vs. 0.56). Besides, the RFDmax was associated with the RMAmax and EMDmax with a significant effect of instruction. Data showed that the instruction given prior contracting muscle affected explosive force production and associated neuromuscular variables. As a result, the “fast” instruction may be preferred in the assessment of explosive force capacity of skeletal muscle during maximal efforts.

Open access