ECSS Paris 2023: OP-MH15
INTRODUCTION: High-Intensity Multimodal Training (HIMT) is promoted as a time‑efficient method for meeting physical activity guidelines by combining high-intensity aerobic and resistance exercise within a single session. However, poor standardisation in prescription and reporting has limited comparisons with other combined training modes (e.g., Inter‑Session Concurrent Training [ISCT]). This study examined the feasibility, acceptability, physical and biochemical outcomes of a 7‑week HIMT intervention compared to an active matched ISCT control, delivered across three community sites. METHODS: A two‑arm parallel randomised controlled trial was conducted. Recreationally active adults were allocated to HIMT (4 × 45‑min sessions/week of combined aerobic and resistance exercise in a circuit format) or ISCT (2 × 45‑min resistance circuits + 2 × 45‑min aerobic circuits/week). Training volume, session duration, exercise intensity (RPE ≥ 7/10 [CR‑10]) and exercise selection were matched between groups. Feasibility and acceptability were evaluated using a convergent mixed-methods approach, integrating qualitative data (thematic content analysis of open-ended survey responses) and quantitative data (Likert scale scores, training session intensity, retention). Physical outcomes (maximal strength, aerobic capacity, anthropometry, body composition) and acute and chronic exercise-induced biochemical responses (cortisol, testosterone, growth hormone) were assessed using linear mixed effect models, pre to-post intervention. A priori sample size n = 47 (α=0.05, power =0.80, f=0.42). RESULTS: 79 participants were randomised and 75 completed post-testing (HIMT n=39, ISCT n=36). Participants attended 91.4% of sessions, with an average training S-RPE of 7.47 ± 1.40. The program was safe, tolerable and enjoyable. Both groups showed small within‑group improvements in lower and upper‑body strength, peak oxygen uptake, and maximum work rate, alongside trivial improvements in fat mass, body fat percentage, lean mass, and waist circumference (p<0.05). A modest group × time interaction favoured ISCT for reduced body fat percentage (b=-0.628, 95% CI [-1.21 to -0.046], p=0.035, d=−0.082). An attenuated exercise-induced growth hormone response was observed following 7-weeks of ISCT compared to HIMT in females only (b= -8.135, 95% CI [-14.737 to -1.533], p=0.017, d=-0.836). Further expected biochemical responses were observed in both groups. CONCLUSION: HIMT is a safe, feasible and acceptable intervention for recreationally active adults, eliciting meaningful physical adaptations over 7-weeks. Both training modes produced expected biochemical adaptations, with more pronounced exercise-induced hormonal responses in females. These findings support the use of HIMT to promote structured exercise engagement and physical fitness, while advancing community based prescription standards for combined training. This may inform future implementation of scalable, time efficient models to promote population health and fitness.
Read CV Tijana SharpECSS Paris 2023: OP-MH15
INTRODUCTION: Physical activity (PA) is associated with major health benefits. Since 2020, the World Health Organization no longer requires PA to be accumulated in bouts of at least 10 minutes. Thus, brief and intermittent episodes now contribute to recommendations (Bull et al., 2020). However, many wearables still rely on 60-s epoch aggregation due to historical technical constraints and alignment with previous guidelines. Such temporal resolution is poorly suited to capture the highly fragmented nature of daily-life PA (Taoum et al., 2021). Moreover, most validation studies are conducted in controlled settings, limiting ecological validity (Giurgiu et al., 2025). Although newer approaches use shorter epochs, few studies have directly compared these methods under free-living conditions. This study compared the validity of several devices and analytical methods to detect walking bouts and classify their intensity in free-living conditions using video-recorded direct observation. METHODS: Sixty healthy adults (20–80 years, balanced by sex and decade) simultaneously wore six devices for seven days: activPAL (thigh), StepWatch4 (ankle), ActiGraph wGT3X-BT (hip and wrist), Fitbit Charge 5 and Inspire 2 (hip and wrist), and Garmin Vívoactive 4S (wrist). A total of 119 free-living sessions were annotated by two raters (>150 h; 10,194 walking bouts; gold standard). For each device, commonly used analytical approaches were tested. Cadence (steps·min⁻¹) derived from detected steps was used to classify intensity (Tudor-Locke et al., 2019). Sensitivity, specificity, and weighted accuracy were computed for walking detection and intensity classification. RESULTS: Three main findings emerged: (1) Aggregation ≥60 s overestimates walking duration and underestimates cadence, leading to an underestimation of moderate-to-vigorous PA in favor of light PA; (2) With high temporal resolution (≤1 s), validity generally depends on sensor location, with thigh-, hip-, and ankle-worn devices better detecting short bouts; however, the wrist-worn StepCount-SSL algorithm (Small et al., 2024) achieved validity comparable to lower-limb and hip placements; (3) At identical location and resolution, analytical choices (counts, vector magnitude, raw-signal-based or machine-learning methods) substantially affect validity. CONCLUSION: Free-living walking is highly fragmented. Ignoring short bouts lead to misestimating walking intensity, a key parameter of PA guidelines. In most cases, combining lower-limb or hip placement with high temporal resolution better reflects real-world walking dynamics. However, advanced wrist-based machine-learning approaches such as StepCount-SSL may overcome traditional wrist-placement limitations. To accurately characterize intermittent walking in daily life, we recommend: (1) high temporal resolution approaches (≤1 s or event-based detection), and (2) sensor placement on the hip, thigh, or ankle, or the use of sufficiently validated wrist-based machine-learning algorithms (e.g., StepCount-SSL).
Read CV Germain FaityECSS Paris 2023: OP-MH15
INTRODUCTION: Exercise exerts a profound effect on cardiac autonomic regulation, as assessed by heart rate variability (HRV). In very old adults, the post-exercise shift toward sympathetic predominance may represent a transient period of increased cardiovascular risk. This imbalance could potentially be mitigated by transcutaneous vagus nerve stimulation (tVNS). We therefore aimed to assess the effects of aerobic exercise and tVNS on HRV in older adults. METHODS: Thirty adults aged ≥75 years were recruited to participate in a 3-month brisk walking program consisting of three 30-minute sessions per week. Participants performed exercise sessions with and without transcutaneous vagus nerve stimulation (tVNS). Short-term HRV was recorded (i) at baseline before exercise, (ii) after the first exercise session, and (iii) after completion of the 3-month training program, as well as at 3 h, 12 h, and 24 h post-exercise. The tVNS device was applied for two hours (i) at rest, (ii) following a single exercise session, and (iii) after completion of the training program. This work constitutes an ancillary study of a clinical trial registered at ClinicalTrials.gov (Identifier: NCT03302923). RESULTS: A repeated-measures general linear model revealed a significant effect of training on parasympathetic activity (lnRMSSD), with a rebound increase observed after 24 h of recovery. A significant interaction between training and tVNS was also detected. CONCLUSION: In very old adults, aerobic exercise appears to enhance HRV, with further improvements associated with tVNS.
Read CV David HUPINECSS Paris 2023: OP-MH15