Downhill running increases markers of muscle damage and impairs the maximal voluntary force production as well as the late phase of the rate of voluntary force development.

PURPOSE: To examined the time-course of the early and late phase of the rate of voluntary force development (RVFD) and muscle damage markers after downhill running. METHODS: Ten recreational runners performed a 30-min downhill run at 10 km h-1 and -20% (-11.3°) on a motorized treadmill. At baseline and each day up to 4 days RVFD, knee extensors maximum voluntary isometric force (MVIC), serum creatine kinase (CK) concentration, quadriceps swelling, and soreness were assessed. The early (0-50 ms) and late (100-200 ms) phase of the RVFD, as well as the force developed at 50 and 200 ms, were also determined. RESULTS: MVIC showed moderate decrements (p < 0.05) and recovered after 4 days (p > 0.05). Force at 50 ms and the early phase were not impaired (p > 0.05). Conversely, force at 200 ms and the late phase showed moderate decrements (p < 0.05) and recovered after 3 and 4 days, respectively (p > 0.05). CK concentration, quadriceps swelling, and soreness increased (p < 0.05) were overall fully resolved after 4 days (p > 0.05). CONCLUSION: Downhill running affected the knee extensors RVFD late but not early phase. The RVFD late phase may be used as an additional marker of muscle damage in trail running.

High Physical Activity Volume Is Associated With an Increase in the Calibre of the Lower Limb Veins Without Impact on Functional Discomfort: the VARISPORT Study.

OBJECTIVE: The relationship between physical activity and lower limb veins is complex. If a sedentary lifestyle is considered to be negative on lower limb veins, specific information on physical activity varicose vein volume is sparse, especially the effect of high physical activity volume. The main objective of the VARISPORT study was to evaluate lower limb veins (clinically, morphologically, and haemodynamically) and chronic venous disease symptoms in subjects exposed to high physical activity volume compared with a group of non-exposed subjects. METHODS: A cross sectional study compared a group of high exercise training volume volunteers (more than eight hours of uninterrupted vigorous intensity physical activity per week for more than six months: high physical activity volume group, HPAV group) with a volunteer control group matched for age, sex, and body mass index. Clinical examination was performed to determine the Clinical, Etiological, Anatomical, Pathophysiological (CEAP) classification of each subject and the Carpentier score was used to assess symptoms related to possible chronic venous disease. Duplex ultrasonography was used to assess vein diameters and reflux in the deep and superficial veins. RESULTS: One hundred and nineteen subjects were included in each group. The lower limb veins (deep and superficial) were significantly more dilated in the HPAV group. More reflux was found in the great saphenous veins and non-saphenous veins in the HPAV group. High physical activity volume was associated with a higher frequency of visible varicose veins (stage C2 of the CEAP classification), odds ratio 3.37 (95% confidence interval 1.66 - 7.25) without impact on functional discomfort (44 subjects with a Carpentier score ≥ 1 in each group). CONCLUSION: The VARISPORT study reported an increase in the calibre of the lower limb veins without impact on functional discomfort. Further studies are needed to determine whether these athletic veins are truly pathological varicose veins or simply an adaptation to high physical activity volumes.

Physically active men present a healthier cardiometabolic profile in response to a balanced meal compared to inactive men.

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.

Cardiometabolic and neuromuscular analyses of the sit-to-stand transition to question its role in reducing sedentary patterns.

To counteract the detrimental health effect of sitting all day long, it has been suggested to regularly break sitting time by standing. However, while the difference in energy expenditure, neuromuscular and/or cardiovascular demand of various postures from lying, sitting, and standing is well documented, little is known regarding the dynamic changes occurring during the sit-to-stand transition itself. The aim of the present study was then to describe the cardiometabolic and neuromuscular responses from sitting to standing and specifically during the time-course of this transition. Twelve healthy young participants were asked to perform standardized raises from sitting posture, while cardiometabolic (cardiorespiratory and hemodynamic variables) and neuromuscular (calf muscles' myoelectrical activity, spinal and supraspinal excitabilities) parameters were monitored. As a result, while there was a rapid adaptation for all the systems after rising, the neuromuscular system displayed the faster adaptation (~ 10 s), then hemodynamic (~ 10 to 20 s) and finally the metabolic variables (~ 30 to 40 s). Oxygen uptake, energy expenditure, ventilation, and heart rate were significantly higher and stroke volume significantly lower during standing period compared to sitting one. In calf muscles, spinal excitability (H-reflexes), was lowered by the sit-to-stand condition, while supraspinal drive (V-wave) was similar, indicating different cortico-spinal balance from sitting to standing. Although very heterogenous among participants in terms of magnitude, the present results showed a rapid adaptation for all the systems after rising and the health benefit, notably in terms of energy expenditure, appears rather modest, even if non negligeable.

Downhill running affects the late but not the early phase of the rate of force development.

PURPOSE: This study aimed to evaluate the acute changes in the knee extensors maximum voluntary isometric contraction force (MVIC), rate of force development (RFD), and rate of EMG rise (RER) following a bout of downhill running. METHODS: MVIC and RFD at 0-50, 50-100, 100-200, and 0-200 ms were determined in thirteen men (22 ± 2 yr) before and after 30 min of downhill running (speed: 10 km h-1; slope: - 20%). Vastus lateralis maximum EMG (EMGmax) and RER at 0-30, 0-50, and 0-75 ms were also recorded. RESULTS: MVIC, RFD0-200, and EMGmax decreased by ~ 25% [Cohen's d = - 1.09 (95% confidence interval: - 1.88/- 0.24)], ~ 15% [d = - 0.50 (- 1.26/0.30)], and ~ 22% [d = - 0.37 (- 1.13/0.42)] (all P < 0.05), respectively. RFD100-200 was also reduced [- 25%; d = - 0.70 (- 1.47/0.11); P < 0.001]. No change was observed at 0-50 ms and 50-100 ms (P ≥ 0.05). RER values were similar at each time interval (all P > 0.05). CONCLUSION: Downhill running impairs the muscle capacity to produce maximum force and the overall ability to rapidly develop force. No change was observed for the early phase of the RFD and the absolute RER, suggesting no alterations in the neural mechanisms underlying RFD. RFD100-200 reduction suggests that impairments in the rapid force-generating capacity are located within the skeletal muscle, likely due to a reduction in muscle-tendon stiffness and/or impairments in the muscle contractile apparatus. These findings may help explain evidence of neuromuscular alterations in trail runners and following prolonged duration races wherein cumulative eccentric loading is high.

The Movesense Medical Sensor Chest Belt Device as Single Channel ECG for RR Interval Detection and HRV Analysis during Resting State and Incremental Exercise: A Cross-Sectional Validation Study.

The value of heart rate variability (HRV) in the fields of health, disease, and exercise science has been established through numerous investigations. The typical mobile-based HRV device simply records interbeat intervals, without differentiation between noise or arrythmia as can be done with an electrocardiogram (ECG). The intent of this report is to validate a new single channel ECG device, the Movesense Medical sensor, against a conventional 12 channel ECG. A heterogeneous group of 21 participants performed an incremental cycling ramp to failure with measurements of HRV, before (PRE), during (EX), and after (POST). Results showed excellent correlations between devices for linear indexes with Pearson's r between 0.98 to 1.0 for meanRR, SDNN, RMSSD, and 0.95 to 0.97 for the non-linear index DFA a1 during PRE, EX, and POST. There was no significant difference in device specific meanRR during PRE and POST. Bland-Altman analysis showed high agreement between devices (PRE and POST: meanRR bias of 0.0 and 0.4 ms, LOA of 1.9 to -1.8 ms and 2.3 to -1.5; EX: meanRR bias of 11.2 to 6.0 ms; LOA of 29.8 to -7.4 ms during low intensity exercise and 8.5 to 3.5 ms during high intensity exercise). The Movesense Medical device can be used in lieu of a reference ECG for the calculation of HRV with the potential to differentiate noise from atrial fibrillation and represents a significant advance in both a HR and HRV recording device in a chest belt form factor for lab-based or remote field-application.

Associations Between Heart Rate Variability-Derived Indexes and Training Load: Repeated Measures Correlation Approach Contribution.

ABSTRACT: Davletyarova, K, Vacher, P, Nicolas, M, Kapilevich, LV, and Mourot, L. Associations between heart rate variability-derived indexes and training load: repeated measures correlation approach contribution. J Strength Cond Res 36(7): 2005-2010, 2022-This study aimed to evaluate whether similar associations between indexes derived from heart rate variability (HRV) analyses and training load (TL) could be obtained by using the commonly used Pearson correlation technique and the repeated measures correlation (rmcorr). Fourteen well-trained swimmers (18.5 ± 1.6 years) participated. The training period lasted 4 weeks with a gradual increase in TL. Daily external TL (exTL) and internal TL (inTL) were summed to obtain a weekly TL, and HRV analyses were performed every Saturday morning. During the 4-week period, exTL and inTL increased (p < 0.05) together with a decrease (p < 0.05) in heart rate and an increase (p < 0.05) of cardiac parasympathetic indexes. No significant correlation was found using Pearson correlation while significant associations were found using rmcorr; considering exTL, positive (mean R-R interval [MeanRR], root mean square of differences between successive RR interval [RMSSD], low frequency [LF], high frequency [HF], instantaneous beat-to-beat variability [SD1], continuous beat-to-beat variability [SD2], SD1/SD2; r from 0.59 to 0.46, p value from <0.001 to 0.002) and negative (mean heart rate [meanHR]; r = -0.55, p < 0.001) associations were found. Considering inTL, positive (MeanRR, RMSSD, LF, HF, HFnu, SD1, SD2, SD1/SD2; r from 0.56 to 0.34, p-value from <0.001 to 0.025) and negative (meanHR, LFnu, LF/HF; r from -0.49 to -0.34, p value from 0.001 to 0.025) associations were found. The rmcorr statistical method was able to show associations between parasympathetic indexes and TL contrary to Pearson correlation analysis. Because rmcorr is specifically designed to investigate within-individual association for paired measures assessed on 2 or more occasions for multiple individuals, it should constitute a tool for future training monitoring researches based on a repeated-measures protocol.

[Prevention and management of running-related injuries]. / Prévention et prise en charge de la blessure liée à la course à pied.

Running related injury is a complex, multifactorial phenomenon that remains difficult to explain. However, there are available tools for clinicians allowing prevention (primary or tertiary) and rehabilitation optimization, thus reducing the consequences of the injury and time before returning to participation. These tools rely mainly on training load monitoring and clinical evaluation of stride biomechanical analysis. Unfortunately, they currently remain poorly known by practitioners, while allowing the opportunity to address the challenge of managing the injured runner, including a faster return to run, but also the prevention of a potential recurrence. It requires targeted intervention and education of the patient on the factors leading to the injury.

La blessure liée à la course à pied est un phénomène complexe, multifactoriel dont l'explication reste difficile. Cependant, des outils à disposition des cliniciens permettent d'agir de manière préventive (primaire ou tertiaire) et d'optimiser la rééducation afin de réduire les conséquences de la blessure et le délai avant la reprise de l'activité. Ces outils portent principalement sur le suivi de la charge d'entraînement et l'utilisation clinique de l'analyse biomécanique de la foulée. Ils sont toutefois aujourd'hui mal connus par les praticiens alors que leur utilisation permet de répondre à l'enjeu de la prise en charge du coureur comprenant un retour le plus rapide possible à la pratique, mais également la prévention d'une potentielle récidive. Cela sous-tend un travail ciblé et une éducation du patient sur les facteurs entraînant la blessure.

Post-exercise cardiac autonomic and cardiovascular responses to heart rate-matched and work rate-matched hypoxic exercise.

PURPOSE: This study investigated the effect of performing hypoxic exercise at the same heart rate (HR) or work rate (WR) as normoxic exercise on post-exercise autonomic and cardiovascular responses. METHODS: Thirteen men performed three interval-type exercise sessions (5 × 5-min; 1-min recovery): normoxic exercise at 80% of the WR at the first ventilatory threshold (N), hypoxic exercise (FiO2 = 14.2%) at the same WR as N (H-WR) and hypoxic exercise at the same HR as N (H-HR). Autonomic and cardiovascular assessments were conducted before and after exercise, both at rest and during active squat-stand manoeuvres (SS). RESULTS: Compared to N, H-WR elicited a higher HR response (≈ 83% vs ≈ 75%HRmax, p < 0.001) and H-HR a reduced exercise WR (- 21.1 ± 9.3%, p < 0.001). Cardiac parasympathetic indices were reduced 15 min after exercise and recovered within 60 min in N and H-HR, but not after H-WR (p < 0.05). H-WR altered cardiac baroreflex sensitivity (cBRS) both at rest and during SS (specifically in the control of blood pressure fall during standing phases) in the first 60 min after the exercise bout (p < 0.05). Post-exercise hypotension (PEH) did not occur in H-HR (p > 0.05) but lasted longer in H-WR than in N (p < 0.05). CONCLUSIONS: Moderate HR-matched hypoxic exercise mimicked post-exercise autonomic responses of normoxic exercise without resulting in significant PEH. This may relate to the reduced WR and the limited associated mechanical/metabolic strain. Conversely, WR-matched hypoxic exercise impacted upon post-exercise autonomic and cardiovascular responses, delaying cardiac autonomic recovery, temporarily decreasing cBRS and evoking prolonged PEH.

Influence of Artefact Correction and Recording Device Type on the Practical Application of a Non-Linear Heart Rate Variability Biomarker for Aerobic Threshold Determination.

Recent study points to the value of a non-linear heart rate variability (HRV) biomarker using detrended fluctuation analysis (DFA a1) for aerobic threshold determination (HRVT). Significance of recording artefact, correction methods and device bias on DFA a1 during exercise and HRVT is unclear. Gas exchange and HRV data were obtained from 17 participants during an incremental treadmill run using both ECG and Polar H7 as recording devices. First, artefacts were randomly placed in the ECG time series to equal 1, 3 and 6% missed beats with correction by Kubios software's automatic and medium threshold method. Based on linear regression, Bland Altman analysis and Wilcoxon paired testing, there was bias present with increasing artefact quantity. Regardless of artefact correction method, 1 to 3% missed beat artefact introduced small but discernible bias in raw DFA a1 measurements. At 6% artefact using medium correction, proportional bias was found (maximum 19%). Despite this bias, the mean HRVT determination was within 1 bpm across all artefact levels and correction modalities. Second, the HRVT ascertained from synchronous ECG vs. Polar H7 recordings did show an average bias of minus 4 bpm. Polar H7 results suggest that device related bias is possible but in the reverse direction as artefact related bias.