ECSS Paris 2023: CP-PN07
INTRODUCTION: Breathing strategies such as Locomotor-Respiratory Coupling (LRC) have the potential to improve ventilatory efficiency and running performance (Harbour et. al, 2022) but have scarcely been reported in field or intervention experiments. It is unknown if digital technologies can guide runners to learn LRC during exercise, and what physiological consequences result. METHODS: Ten female runners completed an outdoor 5k time trial and indoor treadmill test to exhaustion. Runners were familiarized to LRC via a smartphone application (Harbour et. al, 2024) and completed 10 runs independently with the application over four to six weeks. The 5k and treadmill test were repeated after the intervention without LRC specific instruction. Hexoskin smart shirts (Carre Technologies, CAN) were used to detect breathing pattern and LRC. A Suunto smartwatch was used to measure running pace outdoors, while spiroergometry (Cosmed, L.L.C., Rome, Italy) was used indoors. Questionnaires were asked regarding rating of fatigue, breathlessness, and flow. Pre and post-intervention data was compared using paired signed rank tests and Cohen’s d effect sizes. RESULTS: Participants expressed greater degrees of LRC in the post-tests, utilizing mostly 4:1 steps per breath in the outdoor run. Outdoors, runners decreased breathing rate while increasing diaphragmatic contribution (p=0.02, d=1.2) and pulse-respiration quotient (p=0.03, d=0.68) despite no change in running pace (p=0.58). During the indoor run, participants expressed higher tidal volume (p=0.03, d=1.3) especially at VO2max where breathing rate was lower (p=0.04, d=-0.30). No meaningful changes were observed in VO2max, ventilatory efficiency, or questionnaire responses. CONCLUSION: This study demonstrates that LRC can be habituated over a 4-6 intervention period, resulting in changes to breathing pattern in field and indoor maximal conditions. Further investigations are needed using control comparisons and incorporating data from the intervention period.
Read CV Eric HarbourECSS Paris 2023: CP-PN07
INTRODUCTION: Cigarette smoking (CS) is the leading preventable cause of death, causing systemic changes that harmfully impact cardiovascular and pulmonary function at rest and during exercise. Indeed, nicotine overstimulates the sympathetic nervous system, tar alters O2 diffusion, and carbon monoxide reduces O2 transport and extraction (1). Although these effects are well-established in sedentary, middle-aged smokers (SM) with pulmonary disease, limited and controversial studies have focused on young SM without comorbidities (2). Hence, the aim of this study was to evaluate the cardiorespiratory and metabolic kinetics during moderate exercise in young, physically active SM without known lung or cardiovascular disease. It was hypothesized that, despite their brief smoking history and good fitness level, which could mitigate the negative CS effects, SM would exhibit slower kinetics, due to early alterations in oxidative stress, autonomic response and O2 delivery. METHODS: The study enrolled 10 physically active SM (age: 21±2 yr., body mass: 78±6 kg; stature: 1.79±0.07 m; 12±5 cigarette/day for 6±2 yr.; mean±SD) and 12 non-smokers (CTRL; age: 24±3 yr., body mass: 78±9 kg; stature: 1.80±0.08 m) matched for age and exercise habits. Participants completed an incremental test (25W/2 min) on a cycle ergometer to determine the maximum pulmonary oxygen uptake (V’O2max). After pulmonary evaluation, participants performed four 6-min square wave tests at 90% first ventilatory threshold VT1 (3). The time constant (t) for expiratory ventilation (V’E), VO2, heart rate (fH) and cardiac output (Q’) during the increasing (on-phase) and decreasing (off-phase) transients was assessed using a mono-exponential model. RESULTS: Static lung volumes were similar between SM and CTRL; however, SM had lower peak expiratory flow (-21%; P=0.004) and maximal voluntary ventilation (-12%; P=0.004). Additionally, SM had lower V’O2max (3657±325 vs 3397±316 ml·min-1 for CTRL and SM, respectively; P=0.037) and mechanical power at VT1 (201±26 vs 185±16 W for CTRL and SM respectively; P=0.045). During the on-phase, t in SM was longer for fH (+24%; P=0.006), V’O2 (+40%; P=0.009), V’E (+49%; P=0.018) and Q (+22%; P=0.024). Similarly, during the off-phase SM showed longer t for fH (+37%; P=0.014), V’O2 (+20%; P=0.004), V’E (+35%; P=0.045) and Q’ (+51%; P=0.020). CONCLUSION: These results demonstrate that CS negatively impacts cardiorespiratory and metabolic kinetics at moderate exercise, thereby elevating cardiovascular risk in SM, despite their young age, relative short smoking history and physical fitness level. REFERENCES: 1. Muller et al. Front Physiol. 2019 2. Borrelli et al. Med Sci Sports Exerc. 2024 3. Murias et al. Am J Physiol Regul Integr Comp Physiol. 2011
Read CV Marta BorrelliECSS Paris 2023: CP-PN07
INTRODUCTION: Cigarette smoking (CS) has a detrimental impact on cardiorespiratory and metabolic response to exercise. Indeed, CS alters the sympathetic drive of the autonomic nervous system, increases airway resistance and oxidative stress, and impairs oxygen delivery (1). It is well-reported a diminished cardiorespiratory fitness in sedentary, middle-aged smokers (SM) with pulmonary disease, index of higher cardiovascular risk. By contrast, limited and controversial studies exist on CS effects in young, physically active SM with a short history of CS (2). Thus, the study aims to investigate the impact of CS on cardiorespiratory and metabolic kinetics during the onset of a square-wave moderate exercise in this population. METHODS: Ten SM (age: 22±2 yrs, body mass: 78±6 kg, stature:1.79±0.07 m, 11±5 cigarette/day for 6±2 yrs; mean±SD) and 11 non-smokers (CTRL; age: 23±1 yrs, body mass: 78±8 kg, stature: 1.80±0.09 m) completed a pulmonary function evaluation. Then, they performed an incremental step test to assess cardiorespiratory and metabolic variables at peak exercise and the two ventilatory thresholds. Lastly, participants performed four 6-minute square-wave exercise (90% of the first ventilatory threshold) to assess the kinetics of expiratory ventilation (VE), oxygen uptake (VO2) and heart rate (fH) responses. Breath-by-breath values of all these variables were averaged and then fitted by a bi-exponential function to determine the amplitude (AMP) and the time constant (tau) of the cardiorespiratory and metabolic kinetics. RESULTS: Static lung volumes were similar between groups. However, SM showed a reduced peak expiratory flow (8.4±1.8 vs 10.5±1.8 l·s-1, respectively; P=0.01) and lower maximum voluntary ventilation (168±14 vs 191±23 l·min-1; respectively, P=0.01) compared to CTRL. At peak exercise, despite similar VO2 (3384±318 vs 3623±333 ml·min-1; for SM and CTRL, respectively), SM exhibited lower mechanical power output (253±21 vs 278±27 W, respectively; P=0.01) and VE (125±11 vs 139±11 l·min-1, respectively, P=0.02). In addition, SM reached ventilatory threshold earlier than CTRL. During constant moderate exercise, SM displayed prolonged VO2 phase I (tau: 17±9 vs 12±4 s for SM and CTRL, respectively; P=0.03) and reduced phase II amplitude (886±301 vs 1111±295 ml·min-1, for SM and CTRL, respectively; P=0.05). Moreover, SM exhibited a slower fH response during phase II (61±18 vs 48±13 s, respectively; P=0.03). CONCLUSION: The longer cardiorespiratory kinetics demonstrate that CS alters the cardiorespiratory and metabolic responses to exercise even in young, asymptomatic SM with a relatively short smoking history. REFERENCES: 1 - Muller et al. Front Physiol. 2019 2 - Borrelli et al. Med Sci Sports Exerc. 2024
Read CV Asia Angela MotalliECSS Paris 2023: CP-PN07