Features of Metabolic Support of Physical Performance in Highly Trained Cross-Country Skiers of Different Qualifications during Physical Activity at Maximum Load

The purpose of our study was to identify the features of metabolic regulation in highly trained cross-country skiers of different qualifications at different stages of the maximum load test. We examined 124 highly trained cross-country skiers (male, ages 17–24). The group consisted of two subgroups based on their competition performance: 61 nonelite athletes (Group I) and 63 elite athletes (group II), who were current members of the national team of the Komi Republic and Russia. The bicycle ergometer test was performed by using the OxyconPro system (Erich Jaeger, Hoechberg, Germany). All the examined athletes performed the exercise test on a cycle ergometer “until exhaustion”. The results of our research indicate that the studied groups of athletes with high, but different levels of sports qualifications are a convenient model for studying the molecular mechanisms of adaptation to physical loads of maximum intensity. Athletes of higher qualifications reveal additional adaptive mechanisms of metabolic regulation, which is manifested in the independence of serum lactate indicators under conditions of submaximal and maximum power from maximal oxygen uptake, and they have an NO-dependent mechanism for regulating lactate levels during aerobic exercise, including work at the anaerobic threshold.

Athletes’ Physical Performance in the System of the Sports Medicine Technologies Effectiveness Evaluation

Aim. To determine the effectiveness of the specific loading testing use in assessing the athletes’ physical performance. Material and methods. We present a post-hoc analysis of data from specific and nonspecific loading testing (bicycle ergometer, treadmill, rowing ergometer, and ski treadmill) of 23 oarsmen athletes (13 male (mean age 25.85±0.88 years) and 10 female (mean age 22.90±1.20 years); 125 track and field athletes (75 male athletes (mean age 24.74±0.91) and 50 female athletes (mean age 23.81±1.35)), 38 ski athletes (22 male athletes (mean age 21.3±2.4) and 16 female athletes (mean age 19.6±1.8)). Results and discussion. When assessing the physical performance of track and field athletes of various positions using a bicycle ergometer and a treadmill, the maximum oxygen consumption (MOC) parameter for throwers and jumpers was in the range of 29-55 ml/min/kg (it is more appropriate to use a statoergometer), for runners – 39-75 ml/min/kg (testing on a treadmill is preferable). The greatest efficiency and physiological validity was obtained by load testing using a rowing ergometer for rowing athletes and a ski roller treadmill for athletes of ski sports (the ratio of heart rate at the anaerobic metabolism threshold level to the heart rate “on failure” is ~ 97%). With bicycle ergometry, low values of MOC were obtained in athletes training for endurance, and, including on the treadmill, in athletes with the main strength load and implies the work of the muscles of the upper shoulder girdle and back. The functional and reserve capabilities of the athlete are not reflected in the data obtained that makes impossible to judge the level of his/her functional readiness. Conclusion. Sports medicine technologies reflecting the dynamic characteristics of athletes’ physical performance should be evaluated from the point of view of informativeness and efficiency of their application depending on the type of sport. Conclusion about the effectiveness of sports medicine technologies should be made considering the results of the functional and physical performance testing under the exertion, specific to a particular sport.

Modeling Optimal Cadence as a Function of Time during Maximal Sprint Exercises Can Improve Performance by Elite Track Cyclists

In track cycling sprint events, optimal cadence PRopt is a dynamic aspect of fatigue. It is currently unclear what cadence is optimal for an athlete’s performance in sprint races and how it can be calculated. We examined fatigue-induced changes in optimal cadence during a maximal sprint using a mathematical approach. Nine elite track cyclists completed a 6-s high-frequency pedaling test and a 60-s isokinetic all-out sprint on a bicycle ergometer with continuous monitoring of crank force and cadence. Fatigue-free force-velocity (F/v) and power-velocity (P/v) profiles were derived from both tests. The development of fatigue during the 60-s sprint was assessed by fixing the slope of the fatigue-free F/v profile. Fatigue-induced alterations in PRopt were determined by non-linear regression analysis using a mono-exponential equation at constant slope. The study revealed that PRopt at any instant during a 60-s maximal sprint can be estimated accurately using a mono-exponential equation. In an isokinetic mode, a mean PRopt can be identified that enables the athlete to generate the highest mean power output over the course of the effort. Adding the time domain to the fatigue-free F/v and P/v profiles allows time-dependent cycling power to be modelled independent of cadence.

β-Hydroxybutyrate Oxidation in Exercise Is Impaired by Low-Carbohydrate and High-Fat Availability

Purpose: In this study, we determined ketone oxidation rates in athletes under metabolic conditions of high and low carbohydrate (CHO) and fat availability.Methods: Six healthy male athletes completed 1 h of bicycle ergometer exercise at 75% maximal power (WMax) on three occasions. Prior to exercise, participants consumed 573 mg·kg bw−1 of a ketone ester (KE) containing a 13C label. To manipulate CHO availability, athletes undertook glycogen depleting exercise followed by isocaloric high-CHO or very-low-CHO diets. To manipulate fat availability, participants were given a continuous infusion of lipid during two visits. Using stable isotope methodology, β-hydroxybutyrate (βHB) oxidation rates were therefore investigated under the following metabolic conditions: (i) high CHO + normal fat (KE+CHO); (ii) high CHO + high fat KE+CHO+FAT); and (iii) low CHO + high fat (KE+FAT).Results: Pre-exercise intramuscular glycogen (IMGLY) was approximately halved in the KE+FAT vs. KE+CHO and KE+CHO+FAT conditions (both p < 0.05). Blood free fatty acids (FFA) and intramuscular long-chain acylcarnitines were significantly greater in the KE+FAT vs. other conditions and in the KE+CHO+FAT vs. KE+CHO conditions before exercise. Following ingestion of the 13C labeled KE, blood βHB levels increased to ≈4.5 mM before exercise in all conditions. βHB oxidation was modestly greater in the KE+CHO vs. KE+FAT conditions (mean diff. = 0.09 g·min−1, p = 0.03; d = 0.3), tended to be greater in the KE+CHO+FAT vs. KE+FAT conditions (mean diff. = 0.07 g·min−1; p = 0.1; d = 0.3) and were the same in the KE+CHO vs. KE+CHO+FAT conditions (p < 0.05; d < 0.1). A moderate positive correlation between pre-exercise IMGLY and βHB oxidation rates during exercise was present (p = 0.04; r = 0.5). Post-exercise intramuscular βHB abundance was markedly elevated in the KE+FAT vs. KE+CHO and KE+CHO+FAT conditions (both, p < 0.001; d = 2.3).Conclusion: βHB oxidation rates during exercise are modestly impaired by low CHO availability, independent of circulating βHB levels.

Impacts of different intensities of exercise on inflammation and hypoxia markers in low altitude

Background This study aims to determine and compare the effects of exercise modalities with different intensities on the secretion of key inflammation and hypoxia markers in amateur athletes. Methods Twenty-three athletes with a mean age of 20.1 years, living at low altitude (1850 m) participated in this study. The participants' maximal oxygen consumption values (VO2 max) were determined with an incremental cycle exercise test as 54.15 ± 6.14 mL kg min−1. Athletes performed four protocols: at rest, 50% VO2 max, 75% VO2 max and 100% VO2 max (until exhaustion) with one-week intervals. 50% VO2 max, 75% VO2 max sessions were performed continuously for 30 min on a bicycle ergometer and 100% VO2 max session was performed by cycling until exhaustion. Blood samples were obtained at rest and immediately after each exercise session. Serum tumor necrosis factor alpha (TNF-α), C-reactive protein (CRP), interleukin-10 (IL-10), and hypoxia inducible factor-1 alpha (HIF-1α) levels were measured. Results There were significant differences in serum TNF-α levels in 75% VO2 max and 100% VO2 max sessions (489.03 ± 368.37 and 472.70 ± 365.21 ng/L, respectively) compared to rest conditions (331.65 ± 293.52 ng/L). Serum CRP levels of 50% VO2 max and 75% VO2 max sessions (1.19 ± 0.50; 1.07 ± 0.52 mg/L) were significantly higher than the rest condition (0.74 ± 0.35 mg/L). There were significant differences in serum IL-10 levels of rest condition and 50% VO2 max; 50% VO2 max, and 100% VO2 max sessions (328.09 ± 128.87; 446.36 ± 142.84; 347.44 ± 135.69; 324.88 ± 168.06 pg/mL). Serum HIF-1α levels were significantly higher in 75% VO2 max session compared to rest (1.26 ± 0.16; 1.08 ± 0.19 ng/mL) (P < 0.05 for all comparisons). Conclusions Both inflammatory and anti-inflammatory pathway is induced on different exercise intensities. Exercise protocols performed until exhaustion may lead to activation of inflammatory pathways and hypoxia-induced damage.

Comparative Efficacy of Open-chain Kinematics and Closed-chain Kinematics on Walking Proficiency and Societal Integration in Post-stroke Individuals: a Pretest- Post-test Experimental Study

Background Post-stroke hemiplegic gait is a mixture of deviations and compensatory motion dictated by residual function. To improve stroke survivors' walking ability, it is necessary to evaluate different rehabilitation approaches and identify those that have a greater effect on locomotor recovery of stroke patients. Objectives This study was designed to compare the effect of open-chain kinematics (bicycle ergometry) and closed-chain kinematics (treadmill) on walking proficiency in post-stroke individuals and their societal integration. Methods This was a pretest- posttest- experimental study involving 35 ambulatory hemiplegic stroke survivors (18males and 17 females) with a mean age of 53.77±10.95 undergoing rehabilitation at the two Teaching Hospitals in Lagos. Patients went through a 10-week rehabilitation and were randomly assigned to two intervention groups. Spatio-temporal gait parameters were measured by the six-metre walkway and community integrated questionnaire was used to examine home integration, social integration and productive activities. Data were subjected to inferential and descriptive statistics. The level of significance was set at p<0.05. Results Results showed significant difference between baseline and post intervention scores for all the gait parameters in the bicycle ergometer group except for stride length (p = 0.078). There was also a significant difference in the mean change in cadence between the treadmill and bicycle ergometer group (p = 0.04). Conclusions Both open-chain and closed-chain kinematics are effective, but closed- chain is most effective in re-educating ambulation and re-gaining spatio-temporal gait parameters after stroke and should be structured into the patients’ treatment regimen to effectively improve functional capability in post-stroke individuals.

A fan-attached jacket worn in an environment exceeding body temperature suppresses an increase in core temperature

We examined whether blowing hot air above body temperature under work clothing may suppress core temperature. Nine Japanese men engaged in two 30-min bicycle ergometer sessions at a workload of 40% VO2max at 40 °C and 50% relative humidity. The experiment was conducted without wearing any cooling apparatus (CON), wearing a cooling vest that circulated 10.0 °C water (VEST), and wearing a fan-attached jacket that transferred ambient air underneath the jacket at a rate of 30 L/s (FAN). The VEST and FAN conditions suppressed the increases of rectal temperature (CON, VEST, FAN; 38.01 ± 0.19 °C, 37.72 ± 0.12 °C (p = 0.0076), 37.54 ± 0.19 °C (p = 0.0023), respectively), esophageal temperature (38.22 ± 0.30 °C, 37.55 ± 0.18 °C (p = 0.0039), 37.54 ± 0.21 °C (p = 0.0039), respectively), and heart rate (157.3 ± 9.8 bpm, 136.9 ± 8.9 bpm, (p = 0.0042), 137.5 ± 6.5 bpm (p = 0.0023), respectively). Two conditions also reduced the estimated amount of sweating and improved various subjective evaluations. Even in the 40 °C and 50% relative humidity environment, we may recommend wearing a fan-attached jacket because the heat dissipation through evaporation exceeded the heat convection from the hot ambient air.

Cardiorespiratory System During Bicycle Ergometer Testing in Biathletes and Cross-Country Skiers of the Komi Republic

The purpose of this paper was to compare the physiological parameters of the cardiorespiratory system at rest and during the bicycle ergometer test to exhaustion in biathletes and cross-country skiers to identify the difference in the aerobic performance of athletes of two closely related winter sports. Materials and methods: 18 biathletes and 28 male cross-country skiers aged 17–21 years, all with the rank of the Candidate for Master of Sport, were examined. Bicycle ergometer testing to exhaustion was used (Oxycon Pro, Germany), cardiorespiratory parameters were analysed, maximal oxygen consumption (VO2 max) was determined, and the physiological cost of a unit of work was calculated. Results. At rest, a statistically significantly higher level of fitness was revealed in crosscountry skiers compared with biathletes according to such haemodynamic parameters as systolic blood pressure, pulse pressure, and double product. At maximal load, an increased degree of fitness was found in cross-country skiers in terms of power and duration of bicycle ergometer exercise, cardiac and pulse cost per unit of work, as well as gross and specific VO2 max. The body of cross-country skiers under the test to exhaustion (according to oxygen pulse value) functions more efficiently than the body of biathletes. Thus, higher level of fitness among cross-country skiers of the Komi Republic is manifested in the economization of cardiorespiratory functions both at rest and at maximal ergometric loads, as well as in the value of specific physiological cost per unit of work. Increased functionality (or reserves) of cross-country skiers is indicated by such parameters as systolic blood pressure, pulse pressure, double product, respiratory minute volume, oxygen consumption, and energy expenditure. It can be assumed that the aerobic performance of biathletes is lower than that of cross-country skiers as the former receive less training in cross-country skiing.

Psychophysiological processes, ensuring the achievement of sports results

Objective: to investigate the role of psychophysiological processes in achieving sports results.Materials and methods: the driving force of sports behavior was measured in free­divers, basketball players and athletes, which consisted of motivation to achieve sports results, emotional stress, situational information, hypoxic stability, and physical endurance. Then the sportsmen rotated the pedals of the bicycle ergometer with simultaneous intermittent breath holdings from 20 to 60 s.Results: it has been established that all components of the driving force of behavior are necessary for the sports activity of all groups of sportsmen. For the driving force of free­divers’ behavior, hypoxic stability is of greatest importance (r = 0.59), for basketball players — emotional stress (r = 0.6) and for athletes — emotional stress and situational information (r = 0.71 and 0.58). In addition, hypoxic stability and physical endurance directly affect the final sports result (r = 0.7 and 0.65) in conjunction with the driving force of behavior (r = 0.53).Conclusion: sports result is provided by the driving force behind the behavior of sportsmen. For free­divers, hypoxic stability is of primary importance, for basketball players — physical endurance and emotional stress, and for athletes — the totality of all components of the driving force of behavior.

Comparison of cardiovascular responses among physically active and sedentary students: A protocol for Quasi-experimental study of submaximal exercise on a bicycle ergometer in the Sahel region of Africa

BackgroundThe rate at which the heart rate and blood pressure drop following a stimulus such as exercise or physical stress is a powerful and independent marker for determining the rate mortality from a cardiovascular disease. The purpose of this study will be to determine the heart rate and blood pressure drops of physically active and sedentary student following a sub-maximal exercise on a bicycle ergometer.ResultsThis quasi-experimental study will conveniently sample a total of 102 (Physically active n=51 & sedentary n=51) subjects of age 18-35. The study site shall be the physiotherapy gymnasium at the University of Maiduguri Teaching hospital. The level of physical activity will be measured using International Physical Activity questionnaire. Anthropometric variable such as height and weight will be assessed. Borge scale will be used to determine the Rate of Perceived Exertion. Data analysis will be done using SPSS version 20. Student –t-test, Analysis of Co-variance and descriptive statistic will be used to analyzed collected data at p<0.05. The heart rate and blood pressure at rest, peak intensity and post-exercise will be determined using a digital electronic device. The difference between the peak/resting heart rate and blood pressure will be recorded as rate of drops. Measurement will also be carried out at 1, 2-minutes after the first measurement up to 5 minutes after removing exercise stimulus.ConclusionHeart rate and blood pressure recovery are a useful clinical tool for diagnosis of cardiovascular diseases. Drops in heart rate less than 12 beat per minutes put a person at risk of developing a heart attack. It is not known whether the drops in heart rate of student in the Sahel region of Nigeria will be normal or abnormal. Since there are little studies on the recovery heart rate and blood pressure after removing a stimulus such as exercise. There is a need for more studies to help bridge the gap in literatures.