Mikkel Thunestvedt Hansen

A novel method for estimating V̇O₂peak using seismocardiography (SCG eV̇O₂peak) at rest was developed some years ago, and this study investigates an updated version using data from a trained population. Forty five subelite female and Sixty seven elite male football players were tested and included in a cross‐sectional accuracy comparison between SCG eV̇O₂peak and V̇O₂peak obtained from an incremental cardiopulmonary exercise test (CPET) performed on a treadmill. In addition, the ability of the method to detect changes over time was assessed by comparison of changes in V̇O₂peak over 3 months (female and male, n = 60), 6 months (female, n = 17), and 1 year (male, n = 18) for CPET and SCG, respectively. No difference and a fair agreement were found between combined sex cross‐sectional SCG eV̇O₂peak and CPET V̇O₂peak (bias ± 95% CI: −1.0 ± 0.9 mL·min⁻¹·kg⁻¹ and limits of agreement [95%]: ± 9.1 mL·min⁻¹·kg⁻¹), with similar agreement between sexes. The standard error of estimation and mean absolute percentage error were 4.8 mL·min⁻¹·kg⁻¹ and 7.4%, respectively. V̇O₂peak was only increased over 6 months for females (CPET: 2.2 ± 1.1 mL·min⁻¹·kg⁻¹, SCG: 1.2 ± 1.1 mL·min⁻¹·kg⁻¹, and p < 0.05) with no difference between methods (p = 0.170). A correlation between ΔV̇O₂peak for CPET and SCG was found for 1‐year analyses (male, R² = 0.62, and P < 0.05) but no other correlations were significant. The SCG method is accurate in estimating V̇O₂peak in both subelite and elite football players, with fair agreement and low estimation errors. The SCG method was able to detect an association of 1‐year changes but not for changes over shorter times; however, these results require more investigation due to small sample sizes.

Aims: Knowledge of cardiorespiratory fitness (i.e. VO2peak) is important for determining prognosis and prescribing exercise for patients with heart disease undergoing cardiac rehabilitation (CR) programmes. In this explorative study, we investigated the accuracy of a novel equation using seismocardiography (SCG) at rest for the estimation of VO2peak (SCG eVO2peak) and whether it could detect changes following CR. An interim data analysis was planned after 50% of patients had undergone testing, allowing for adjustment of the SCG eVO2peak. We compared the SCG eVO2peak with a cardiopulmonary exercise test (CPET). Methods and results: We included 125 patients with new-onset ischaemic heart disease (IHD, n = 58) or heart failure with reduced left ventricular ejection fraction (HFrEF, n = 67) from an outpatient CR clinic. Testing included SCG eVO2peak and CPET measurement. The adjusted SCG 4.7_HD was validated in 30 and 34 patients with IHD and HFrEF, respectively. Forty-four out of the 67 patients with HFrEF were tested after completing 12 weeks of CR. A mean absolute percentage error (MAPE) ≤10% was decided for clinical relevance. The SCG 4.7_HD overestimated VO2peak (2.1 mL min−1 kg−1, P = 0.003) with 95% limits of agreement ranging ±10.9 mL min−1 kg−1 when compared with CPET. The standard error of estimation was 6.0 mL min−1 kg−1, and MAPE was 29.1%. No correlation was observed between delta SCG 4.7_HD and CPET after CR for patients with HFrEF. Conclusion: The SCG eVO2peak is not supported for clinical purposes in patients with IHD or HFrEF based on a poor-to-moderate agreement with large estimation errors and the inability to detect changes following CR. Trial registration: The study is registered at ClinicalTrials.gov (NCT05520307).

To evaluate the effects of prolonged endurance exercise on the thin‐walled chambers of the right ventricle (RV) and left atrium (LA), and heart rate (HR) in young (YA) and older (OA) athletes. Seven YA and seven OA (30 ± 5 and 65 ± 6 years; V̇O₂max: 61.5 ± 2.2 and 46.8 ± 4.1 mL/min/kg, respectively) were studied before, during, and after a 15‐day cycling journey from Copenhagen (CPH) to Palermo (PMO) (~3000 km). Transthoracic echocardiography (TTE) was performed in both groups, and additional stress echocardiography (SE) in OA. Speckle‐tracking echocardiography was applied for RV free‐wall strain, LA global peak‐atrial longitudinal strain (PALS), and contraction strain (PACS). Assessments were made at baseline (CPH), at arrival (PMO), and for OA six months post‐intervention (CPH+6). RV size and function were similar between YA and OA at baseline and remained unchanged at rest post‐intervention. In OA, SE revealed decreased RV function during exercise at PMO, normalizing at CPH+6. LA size remained unchanged, but OA showed higher baseline filling pressure (E/e′), PACS, and LA stiffness index with lower PALS than YA. Post‐intervention, PALS decreased (p < 0.01) while E/e′, PACS, and LA stiffness index remained stable. Resting HR increased in OA (p = 0.002) but not in YA. V̇O₂max was higher in YA and decreased in OA post‐intervention (p = 0.056). Although RV size and resting function were unaffected, RV exercise‐induced dysfunction was observed in OA, potentially due to increased LA stiffness. These findings suggest age‐related cardiac fatigue and extended recovery time in OA.

Purpose: This study aimed to investigate the validity and applicability of a non-exercise estimation of cardiorespiratory fitness using resting seismocardiography (SCG eV̇O₂peak) in people with overweight and obesity before and after a 14-week lifestyle intervention. Methods: The study was carried out at a Folk high school that offers 14-week courses on lifestyle changes where participants live at the school and voluntarily participate in daily lectures and activities. Sixty-seven men and women with age and body mass index between 18 and 70 years and 25–50 kg·m^–2 were tested at baseline, and 52 had a follow-up test after 14 weeks. Testing included the determination of anthropometric variables, an SCG eV̇O₂peak at supine rest, and a gold standard V̇O₂peak test on a cycle ergometer until voluntary exhaustion. Results: Agreement analysis for V̇O₂peak at baseline (n = 67, SCG eV̇O₂peak: 26.9 ± 1.9 ml·min^–1·kg^–1, V̇O₂peak: 26.6 ± 1.6 ml·min^–1·kg^–1, mean ± 95% confidence interval) showed a bias of 0.3 ± 1.0 ml·min^–1·kg^–1 with 95% limits of agreement (LoA) ranging ± 9.8 ml·min^–1·kg^–1. A Pearson’s correlation of r = 0.78 (p < 0.0001) and a standard error of estimate (SEE) of 5.0 ml·min^–1·kg^–1 were found between methods. At follow-up (n = 52), body mass was reduced by 6.6 ± 1.4 kg (p < 0.0001). V̇O₂peak increased by 3.3 ± 0.9 ml·min^–1·kg^–1 and 175 ± 78 ml·min^–1 and SCG eV̇O₂peak by 2.6 ± 0.8 ml·min^–1·kg^–1 and 93 ± 76 ml·min^–1 (two-way ANOVA repeated measure: intervention p < 0.0001, method p = 0.939 and interaction p = 0.125, relative V̇O₂peak). A Pearson’s correlation of r = 0.37 (p < 0.05) was found between changes in relative V̇O₂peak but not for absolute V̇O₂peak r = 0.10 (p = 0.402). Conclusions: The SCG method is accurate for estimating V̇O₂peak and appropriate for detecting group changes in both relative and absolute V̇O₂peak following a lifestyle intervention in people with overweight and obesity. Furthermore, the method can detect individual changes in V̇O₂peak but not independently of body mass changes. Yet, the applicability is still limited by the relatively large variation in LoA and SEE.

A non‐exercise method equation using seismocardiography for estimating V̇O₂peak (SCG V̇O₂peak) has previously been validated in healthy subjects. However, the performance of the SCG V̇O₂peak within a trained population is unknown, and the ability of the model to detect changes over time is not well elucidated. Forty‐seven sub‐elite football players were tested at the start of pre‐season (SPS) and 36 players completed a test after eight weeks at the end of the pre‐season (EPS). Testing included an SCG V̇O₂peak estimation at rest and a graded cardiopulmonary exercise test (CPET) on a treadmill for determination of V̇O₂peak. Agreement between SCG V̇O₂peak and CPET V̇O₂peak showed a large underestimation at SPS (bias ± 95% CI: −9.9 ± 1.8, 95% Limits of Agreement: 2.2 to −22.0 mL·min⁻¹ kg⁻¹). At EPS no interaction (p = 0.3590) but a main effect of time (p < 0.0001) and methods (p < 0.0001) was observed between SCG and CPET V̇O₂peak. No correlation in V̇O₂peak changes was observed between SCG and CPET (r = −20.0, p = 0.2484) but a fair agreement in classifying the correct directional change in V̇O₂peak with the SCG method was found (Cohen's κ coefficient = 0.28 ± 0.25). Overall, the SCG V̇O₂peak method lacks accuracy and despite being able to estimate group changes, it was incapable of detecting individual changes in V̇O₂peak following a pre‐season period in sub‐elite football players. The SCG algorithm needs to be further adjusted and the accuracy and precision improved for the method to be applicable for use within a trained population.

Purpose: In Football, the high‐intensity running bouts during matches are considered decisive. Interestingly, recent studies showed that peak fat oxidation rates (PFO) are higher in football players than other athletes. This study aimed to investigate whether PFO increases following a pre‐season. Secondarily, and due to COVID‐19, we investigated whether PFO is related to the physical performance in a subgroup of semi‐professional male football players. Methods: Before and after 8 weeks of pre‐season training, 42 sub‐elite male football players (18 semi‐professionals and 24 non‐professionals) had a dual‐energy x‐ray absorptiometry scan and performed a graded exercise test on a treadmill for the determination of PFO, the exercise intensity eliciting PFO (Fatmax) and peak oxygen uptake (V̇O ₂ peak). Additionally, the semi‐professional players performed a Yo‐Yo Intermittent Recovery Test level 2 (YYIR2) before and after pre‐season training to determine football‐specific running performance. Results: PFO increased by 11 ± 10% (mean ± 95% CI), p = 0.031, and V̇O ₂ peak increased by 5 ± 1%, p < 0.001, whereas Fatmax was unchanged (+12 ± 9%, p = 0.057), following pre‐season training. PFO increments were not associated with increments in V̇O ₂ peak (Pearson's r ² = 0.00, p = 0.948) or fat‐free mass (FFM) ( r ² = 0.00, p = 0.969). Concomitantly, YYIR2 performance increased in the semi‐professional players by 39 ± 17%, p < 0.001, which was associated with changes in V̇O ₂ peak ( r ² = 0.35, p = 0.034) but not PFO ( r ² = 0.13, p = 0.244). Conclusions: PFO, V̇O ₂ peak, and FFM increased following pre‐season training in sub‐elite football players. However, in a subgroup of semi‐professional players, increments in PFO were not associated with improvements in YYIR2 performance nor with increments in V̇O ₂ peak and FFM.

Introduction: Liver fat (LF) and visceral adipose tissue (VAT) content decreases with training, however, this has mainly been investigated in sedentary obese or healthy participants. The aim of this study was to investigate the effects of repeated prolonged exercise on LF and VAT content in well‐trained older men and to compare baseline LF and VAT content to recreationally active older men. Method: A group of five well‐trained older men were tested before and after cycling a total distance of 2558 km in 16 consecutive days. VAT content and body composition was measured using DXA before a bicycle ergometer test was performed to determine maximal fat oxidation (MFO), maximal oxygen consumption (), and the relative intensity at which MFO occurred (Fat _max ). LF content was measured on a separate day using MRI. For comparison of baseline values, a control group of eight healthy age‐ and BMI‐matched recreationally active men were recruited. Results: The well‐trained older men had lower VAT ( p = 0.02), and a tendency toward lower LF content ( p = 0.06) compared with the control group. The intervention resulted in decreased LF content ( p = 0.02), but VAT, fat mass, and lean mass remained unchanged. , MFO, and Fat _max were not affected by the intervention. Conclusion: The study found that repeated prolonged exercise reduced LF content, but VAT and remained unchanged. Aerobic capacity was aligned with lower LF and VAT in older active men.

Background The aim was to investigate the effect of prolonged endurance exercise on adipose tissue inflammation markers and mitochondrial respiration in young and old men. Methods Young (aged 30 years, n = 7) and old (aged 65 years, n = 7) trained men were exposed to an exercise intervention of 15 consecutive days biking 7-9 hours/day at 63% and 65% of maximal heart rate (young and old, respectively), going from Copenhagen, Denmark to Palermo, Italy. Adipose tissue was sampled from both the gluteal and abdominal depot before and after the intervention. Mitochondrial respiration was measured by high-resolution respirometry and adipose inflammation was assessed by immunohistochemical staining of paraffin embedded sections. Results An increased number of CD163 + macrophages was observed in both the gluteal and abdominal depot (P < 0.01). In addition, an increased mitochondrial respiration was observed in the abdominal adipose tissue from the young group with complex I (CI_p) stimulated respiration, complex I + II (CI + II_p) stimulated respiration and the capacity of the electron transport system (ETS)(P < 0.05), and in the old group an increase in CI_p and CI + II_p stimulated respiration (P < 0.05) was found. Conclusion Overall, we found a positive effect of prolonged endurance exercise on adipose tissue inflammation markers and mitochondrial respiration in both young and old trained men, and no sign of attenuated function in AT with age.

It has recently been established that myosin, the molecular motor protein, is able to exist in two conformations in relaxed skeletal muscle. These conformations are known as the super-relaxed (SRX) and disordered-relaxed (DRX) states and are finely balanced to optimize ATP consumption and skeletal muscle metabolism. Indeed, SRX myosins are thought to have a 5- to 10-fold reduction in ATP turnover compared with DRX myosins. Here, we investigated whether chronic physical activity in humans would be associated with changes in the proportions of SRX and DRX skeletal myosins. For that, we isolated muscle fibers from young men of various physical activity levels (sedentary, moderately physically active, endurance-trained, and strength-trained athletes) and ran a loaded Mant-ATP chase protocol. We observed that in moderately physically active individuals, the amount of myosin molecules in the SRX state in type II muscle fibers was significantly greater than in age-matched sedentary individuals. In parallel, we did not find any difference in the proportions of SRX and DRX myosins in myofibers between highly endurance- and strength-trained athletes. We did however observe changes in their ATP turnover time. Altogether, these results indicate that physical activity level and training type can influence the resting skeletal muscle myosin dynamics. Our findings also emphasize that environmental stimuli such as exercise have the potential to rewire the molecular metabolism of human skeletal muscle through myosin.