Spatio-temporal running parameters and their variability help to determine a runner's running style. However, determining whether a change is due to the measurement or to a specific condition such as ...an injury is a matter of debate, as no recommendation on the number of steps required to obtain reliable assessments exists.
What is the optimal number of steps required to measure different spatio-temporal parameters and study their variability at different running speeds?
Twenty-five runners performed three experimental sessions of three bouts of treadmill running at 8, 10 and 12 km/h separated by 24 h. We measured cadence, stride, step, contact and flight time. We calculated the duty factor and the leg stiffness index (Kleg). Mean spatio-temporal parameters and linear (coefficient of variation, standard deviation) and non-linear (Higuchi fractal index, α1 coefficient of detrended fluctuation analysis) analyses were computed for different numbers of steps. Relative reliability was determined using the intraclass coefficient correlation. The minimal number of steps which present a good reliability level was considered as the optimal number of steps for measurement. Absolute reliability was assessed by calculating minimal detectable change.
To assess the mean values of spatio-temporal running parameters, between 16 and 150 steps were required. We were unable to obtain an optimal number of steps for cadence, stride and step-time variabilities for all speeds. For the linear analyses, we deduced the optimal number of steps for Kleg and the contact time (around 350 steps). Non-linear analyses measurements required between 350 and 540 steps, depending on the parameter.
Researchers and clinicians should optimize experimental conditions (number of steps and running speed) depending on the parameter or the variability analysis targeted. Future studies must use absolute reliability metrics to report changes in response to a specific condition with no bias due to measurement error.
•The number of steps for a reliable measurement depends on speed and analysis targeted.•The assessment of the mean values of spatio-temporal parameters required from 16 to 144 steps.•The assessment of linear variability of spatio-temporal parameters required from 112 to 384 steps.•The assessment of non-linear variability of spatio-temporal parameters required from 144 to 544 steps.•Cadence, stride and step time variability couldn’t be reliably measured with 6 min of running.
ABSTRACTYoung, D, Malone, S, Beato, M, Mourot, L, and Coratella, G. Iidentification of maximal running intensities during elite hurling match-play. J Strength Cond Res 34(9)2608–2617, 2020—The ...current study aimed to describe the duration-specific running intensities of elite hurling players during competition with respect to position using a rolling average method. Global positioning systems (10-Hz Viper; STATSport, Viper, Newry, Northern Ireland) were used to collect data from 36 elite hurling players across 2 seasons. Players were categorized according to playing positions (full-backs, half-backs, midfielders, half-forwards, and full-forwards). A total of 230 full match samples were obtained from 22 competitive games for analysis. The velocity-time curve was analyzed using a rolling average method, in which the maximum relative total distance (TD; m·min), high-speed running distance (HSR; m·min), and sprint distance (SD; m·min) intensities were calculated across 10 different rolling time durations (1–10 minutes) within each game. There were large to very large (effect sizes ES = 0.66–4.33) differences between 1 minute rolling averages and all other durations for TD, HSR, and SD. However, pairwise comparisons between 6 and 10 minutes for TD, HSR, and SD were smaller and more variable (ES = 0.07, trivial to ES = 0.85, moderate). Half-backs, midfielders, and half-forwards achieved a higher maximal relative TD and HSR in all duration-specific fields when compared with full-backs and full-forwards. No positional difference was observed in 1- and 2-minute durations for SD. Because the rolling average duration increased the maximum TD, HSR and SD running intensities decreased across all positions. These data provide knowledge of the peak running intensities of elite hurling competition and can be used to design training activities to sufficiently prepare players for these “worst-case scenarios.”
Rehabilitation programs involving immersed exercises are more and more frequently used, with severe cardiac patients as well.
This study investigated whether a rehabilitation program including ...water-based exercises has additional effects on the cardiovascular system compared with a traditional land-based training in heart disease patients.
Twenty-four male stable chronic heart failure patients and 24 male coronary artery disease patients with preserved left ventricular function participated in the study. Patients took part in the rehabilitation program performing cycle endurance exercises on land. They also performed gymnastic exercises either on land (first half of the participants) or in water (second half). Resting plasma concentration of nitric oxide metabolites (nitrate and nitrite) and catecholamine were evaluated, and a symptom-limited exercise test on a cycle ergometer was performed before and after the rehabilitation program.
In the groups performing water-based exercises, the plasma concentration of nitrates was significantly increased (P = 0.035 for chronic heart failure and P = 0.042 for coronary artery disease), whereas it did not significantly change in the groups performing gymnastic exercise on land. No changes in plasma catecholamine concentration occurred.
In every group, the cardiorespiratory capacity of patients was significantly increased after rehabilitation. The water-based exercises seemed to effectively increase the basal level of plasma nitrates. Such changes may be related to an enhancement of endothelial function and may be of importance for the health of the patients.
Abstract Background Exercise training is included in cardiac rehabilitation programs to enhance physical capacity and cardiovascular function. Among the existing rehabilitation programs, exercises in ...water are increasingly prescribed. However, it has been questioned whether exercises in water are safe and relevant in patients with stable chronic heart failure (CHF), coronary artery disease (CAD) with normal systolic left ventricular function. The goal was to assess whether a rehabilitation program, including water-based gymnastic exercises, is safe and induces at least similar benefits as a traditional land-based training. Methods and Results Twenty-four male CAD patients and 24 male CHF patients with stable clinical status participated in a 3-week rehabilitation. They were randomized to either a group performing the training program totally on land (CADl, CHFl; endurance + callisthenic exercises) or partly in water (CADw, CHFw; land endurance + water callisthenic exercises). Before and after rehabilitation, left ventricular systolic and cardiorespiratory functions, hemodynamic variables and autonomic nervous activities were measured. No particular complications were associated with both of our programs. At rest, significant improvements were seen in CHF patients after both types of rehabilitation (increases in stroke volume and left ventricular ejection fraction LVEF) as well as a decrease in heart rate (HR) and in diastolic arterial pressure. Significant increases in peaks V ˙ O 2 , HR, and power output were observed in all patients after rehabilitation in exercise test. The increase in LVEF at rest, in HR and power output at the exercise peak were slightly higher in CHFw than in CHFl. Conclusions Altogether, both land and water-based programs were well tolerated and triggered improvements in cardiorespiratory function.
ABSTRACTYoung, D, Beato, M, Mourot, L, and Coratella, G. Match-play temporal and position-specific physical and physiological demands of senior hurlers. J Strength Cond Res 34(6)1759–1768, 2020—The ...aims of the current study were to examine the temporal differences in match-running performances and heart rate (HR) in elite senior hurling players between halves of play and field positions. Global positioning systems (10 Hz) and HR monitors were used to collect data from 48 players over 18 games. Running performances (total distance TD, relative distance, high-speed running HSR, sprint efforts SE, mean length of sprints, and sprint distance SD) and HR values (HRmean and HRpeak) were assessed. Decrements in TD (p = 0.009, effect size ES = −0.15), relative distance (p = 0.009, ES = −0.18), HSR (p = 0.001, ES = −0.28), SE (p = 0.001, ES = −0.23), SD (p = 0.001, ES = −0.24), HRmean (p < 0.001, ES = −0.38), and HRpeak (p < 0.001, ES = −0.21) were found between halves. Half backs showed between-half decrements in all metrics (p < 0.05) except SD (p = 0.130, ES = −0.26). Midfielders (p < 0.001, ES = −0.68) and half forwards (p < 0.001, ES = −0.79) experienced second-half decrements in HSR. No decrements (p > 0.05) in running performances were found between halves for full backs. HRmean was lower in full backs (p = 0.007, ES = −0.46) and half backs (p = 0.001, ES = −0.76) in the second half. Coaches should consider the specific HSR between-half temporal decrements in half backs, midfielders, and half forwards, and customize training program design to minimize these decrements.
Initially suggested as simple cell debris, cell-derived microvesicles (MVs) have now gained acceptance as recognized players in cellular communication and physiology. Shed by most, and perhaps all, ...human cells, these tiny lipid-membrane vesicles carry bioactive agents, such as proteins, lipids and microRNA from their cell source, and are produced under orchestrated events in response to a myriad of stimuli. Physical exercise introduces systemic physiological challenges capable of acutely disrupting cell homeostasis and stimulating the release of MVs into the circulation. The novel and promising field of exercise-derived MVs is expanding quickly, and the following work provides a review of the influence of exercise on circulating MVs, considering both acute and chronic aspects of exercise and training. Potential effects of the MV response to exercise are highlighted and future directions suggested as exercise and sports sciences extend the realm of extracellular vesicles.
Eccentric cycling (ECC) has attracted attention as a method to improve muscle strength and aerobic fitness in populations unable to tolerate conventional methods. However, agreement on exercise ...prescription targets have been problematic. The current report is an initial exploration of a potentially useful tool, a nonlinear heart rate (HR) variability (HRV) index based on the short-term scaling exponent alpha1 of detrended fluctuation analysis (DFA a1), which has been previously shown to correspond to exercise intensity. Eleven male volunteers performed 45 min of concentric (CON) cycling and ECC separated by 1 month. Work rates were matched for HR (~50% of the maximal HR) during the first 5 min and remained stable thereafter. HRV, HR, oxygen consumption (VO
), and cycling power were monitored and evaluated at elapsed times of 10 (T10) and 45 (T45) minutes duration. HR significantly increased between ECC T10 and ECC T45 (
= 0.003, d = 1.485), while DFA a1 significantly decreased (
= 0.004, d = 1.087). During CON, HR significantly increased (
< 0.001 d = 1.570) without significant DFA a1 change (
= 0.48, d = 0.22). Significantly higher HR was observed at T45 in ECC than in CON (
= 0.047, d = 1.059). A session of unaccustomed ECC lead to decreased values of DFA a1 at T45 in comparison to that seen with CON at similar VO
. ECC lead to altered autonomic nervous system balance as reflected by the loss of correlation properties compared to CON.
Purpose
Post-meal cardiometabolic responses are critical for health, and may be influenced by physical activity. The objective of this study was to investigate the effect of habitual physical ...activity level on the metabolic, autonomic nervous system and cardiovascular responses to a balanced meal in healthy men.
Methods
12 active and 12 inactive healthy males, matched for age and body composition, attended the laboratory in fasting condition. Participants were asked to sit quietly and comfortably in an armchair for the whole duration of the experiment (~ 2h30). Metabolic, autonomic nervous system and cardiovascular measurements were performed in fasting conditions, and at regular intervals until one hour after the end of a balanced breakfast.
Results
No significant difference was observed between groups in glycaemia or energy expenditure throughout the experiment. Fat oxidation rate was significantly higher one-hour post-meal in active vs inactive men (Respiratory Quotient: 0.78 ± 0.04
vs
0.88 ± 0.03;
p
< 0.01). Heart rate was significantly lower in active compared to inactive individuals (
p
< 0.001) throughout the experiment and active participants displayed significantly enhanced vagal tone one-hour post-meal (square root of the sum of successive differences between adjacent normal R–R intervals squared: 72.4 ± 27.9 vs 46.4 ± 14.1 ms;
p
< 0.05).
Conclusion
In healthy men, habitual physical activity level seems discriminant to decipher specific profiles in terms of cardiometabolic responses to a meal. Overall, it may suggest pre-signal cardiometabolic impairments in healthy inactive individuals and highlight the need to consider primary prevention in inactive subjects as a key factor for health management.
A lower duty factor (DF) reflects a greater relative contribution of leg swing versus ground contact time during the running step. Increasing time on the ground has been reported in the scientific ...literature to both increase and decrease the energy cost (EC) of running, with DF reported to be highly variable in runners. As increasing running speed aligns running kinematics more closely with spring-mass model behaviours and re-use of elastic energy, we compared the centre of mass (COM) displacement and EC between runners with a low (DF
) and high (DF
) duty factor at typical endurance running speeds. Forty well-trained runners were divided in two groups based on their mean DF measured across a range of speeds. EC was measured from 4 min treadmill runs at 10, 12 and 14 km h
using indirect calorimetry. Temporal characteristics and COM displacement data of the running step were recorded from 30 s treadmill runs at 10, 12, 14, 16 and 18 km h
Across speeds, DF
exhibited more symmetrical patterns between braking and propulsion phases in terms of time and vertical COM displacement than DF
DF
limited global vertical COM displacements in favour of horizontal progression during ground contact. Despite these running kinematics differences, no significant difference in EC was observed between groups. Therefore, both DF strategies seem energetically efficient at endurance running speeds.
PDF
