Background Mobile health interventions, especially smartphone applications (apps), have been proposed as promising interventions for supporting adherence to healthy behaviour in patients post cardiac rehabilitation (CR). The overall aim of the study was to examine the effect of individualized follow-up with an app for one year on peak oxygen uptake (VO2peak) in patients completing CR. Design The study was designed as a single-blinded multicentre randomized controlled trial. Methods The intervention group (IG) received individualized follow-up enabled with an app for one year, while the control group (CG) received usual care. The primary outcome was difference in VO2peak. Secondary outcomes included exercise performance (time to exhaustion, peak incline (%) and peak velocity (km/h)), bodyweight, resting blood pressure, lipid profile, triglycerides, exercise habits, health-related quality of life, health status and self-perceived goal achievement. Results In total, 113 patients completing CR (73.4% with coronary artery disease, 16.8% after valve surgery and 9.8% with other heart diseases) were randomly allocated to the IG or CG. Intention to treat analyses showed a statistically significant difference in VO2peak between the groups at follow-up of 2.2 ml/kg/min, 95% confidence interval 0.9–3.5 ( p < 0.001). Statistically significant differences were also observed in exercise performance, exercise habits and in self-perceived goal achievement. Conclusions Individualized follow-up for one year with an app significantly improved VO2peak, exercise performance and exercise habits, as well as self-perceived goal achievement, compared with a CG in patients post-CR. There were no statistically significant differences between the groups at follow-up in the other outcome measures evaluated.

The aim of the present study was to investigate the performance and aerobic endurance effects of high-intensity (HICR) versus moderate-intensity continuous running (MICR), which were nonmatched for total work. Twenty healthy recreational athletes (aged 28 ± 5 years) were randomly assigned to an HICR, MICR, or no-intervention control (C) group. The HICR group (n = 7) performed a 20-min strenuous, almost exhausting, run above lactate threshold (LT) at ∼88% of maximal heart rate (HRmax), whereas the MICR group (n = 7) performed a 40-min run at ∼80% HRmax. Both the HICR and MICR groups performed 3 intervention sessions a week, in addition to ∼60% of their regular aerobic exercise, for 10 weeks. The C group (n = 6) performed regular physical exercise throughout the study. Time to exhaustion, during a ∼4–8-min ramp test procedure, was significantly increased by 23% and 24% (P < 0.01) following HICR or MICR, respectively, with no significant difference in the change in time to exhaustion (P = 1.00) at pre- to post-training between the 2 training modalities (HICR and MICR). In the HICR group, maximal oxygen consumption and velocity at LT increased significantly by 5.0% and 6.8% (P < 0.01), respectively. The MICR group increased relative maximal oxygen consumption (mL·kg−1·min−1) significantly by 4.7% (P < 0.05), whereas the pulmonary respiratory gas-exchange ratio was significantly decreased at a submaximal workload by 4.2% (P < 0.01), indicating enhanced fat oxidation. No performance or physiological effects were observed in the C group. The present study indicates that even with a substantially lower total energy turnover, HICR can be as performance enhancing as MICR. Moreover, HICR can increase maximal aerobic power, whereas MICR may enhance fat oxidation.

The purpose of this case study was to examine the short-term development of performance and aerobic endurance following prolonged low-intensity ski trekking (LIST) in an Arctic region. Two male recreational athletes (aged 24 and 26 years) with high aerobic fitness performed LIST 7 ± 2 h·day−1 for 23 consecutive days, while hauling sledges (∼80 kg initially) with supplies from the north to the south of Svalbard (∼640 km). Time to exhaustion, maximal oxygen uptake (V̇O2max), lactate threshold (LT) and work economy were evaluated at pre- and post-trek. The results showed that the absolute and relative exercise intensity during LIST were ∼3.9 km·h−1 and ∼60% of maximal heart rate, respectively. Time to exhaustion during a ∼4–6 min ramp walking test, and a >45 min stepwise walking test, while pulling 12.5 kg weights (simulation of ski trekking with loaded sledge), increased by 11–17% and 3–9%, respectively, following LIST. Body mass and V̇O2max relative to body mass (ml·kg−1·min−1) decreased by 5–8% and increased by 3–8%, respectively. Furthermore, the workload associated with LT and LT percentage of V̇O2max increased by 39–69% and 12–13%, respectively. No notable change in work economy was observed. The mean pace during LIST (∼3.9 km·h−1) corresponded to the treadmill walking speed (4 km·h−1) with the lowest oxygen cost (mL·kg−1·m−1) in both participants. It can be concluded that short-term prolonged LIST can improve ski trek-simulated performance and fractional utilisation of V̇O2max in recreational athletes with high aerobic fitness. Moreover, highly aerobically fit ski trekkers appear to instinctively choose the most energy-efficient pace during LIST.

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