In this study we explore how music can entrain human walkers to synchronise to the musical beat without being instructed to do so. For this, we use an interactive music player, called D-Jogger, that senses the user's walking tempo and phase. D-Jogger aligns the music by manipulating the timing difference between beats and footfalls. Experiments are reported that led to the development and optimisation of four alignment strategies. The first strategy matched the music's tempo continuously to the runner's pace. The second strategy matched the music's tempo at the beginning of a song to the runner's pace, keeping the tempo constant for the remainder of the song. The third alignment starts a song in perfect phase synchrony and continues to adjust the tempo to match the runner's pace. The fourth and last strategy additionally adjusts the phase of the music so each beat matches a footfall. The first two strategies resulted in a minor increase of steps in phase synchrony with the main beat when compared to a random playlist, the last two strategies resulted in a strong increase in synchronised steps. These results may be explained in terms of phase-error correction mechanisms and motor prediction schemes. Finding the phase-lock is difficult due to fluctuations in the interaction, whereas strategies that automatically align the phase between movement and music solve the problem of finding the phase-locking. Moreover, the data show that once the phase-lock is found, alignment can be easily maintained, suggesting that less entrainment effort is needed to keep the phase-lock, than to find the phase-lock. The different alignment strategies of D-Jogger can be applied in different domains such as sports, physical rehabilitation and assistive technologies for movement performance.

BackgroundCKD is associated with several comorbidities, cardiovascular disease being the most significant. Aerobic training has a beneficial effect on cardiovascular health in healthy and some well-defined non-healthy populations. However, the effect of aerobic training on glomerular filtration rate in patients with CKD stages 3–4 is unclear.ObjectiveTo review the effects of aerobic exercise training on kidney and cardiovascular function in patients with chronic kidney disease (CKD) stages 3–4.MethodsA random-effects meta-analysis was performed to analyse published randomized controlled trials through February 2018 on the effect of aerobic training on estimated glomerular filtration rate, blood pressure and exercise tolerance in patients with CKD stages 3–4. Web of Science, PubMed and Embase databases were searched for eligible studies.Results11 randomized controlled trials were selected including 362 participants in total. Favourable effects were observed on estimated glomerular filtration rate (+2.16 ml/min per 1.73m2; [0.18; 4.13]) and exercise tolerance (+2.39 ml/kg/min; [0.99; 3.79]) following an on average 35-week aerobic training program when compared to standard care. No difference in change in blood pressure was found.ConclusionsThere is a small beneficial effect of aerobic training on estimated glomerular filtration rate and exercise tolerance, but not on blood pressure, in patients with CKD stages 3–4. However, data are limited and pooled findings were rated as of low to moderate quality.

We investigated whether muscle and ventilatory responses to incremental ramp exercise would be influenced by aerobic fitness status by means of a cross-sectional study with a large subject population. Sixty-four male students (age: 21.2 ± 3.2 years) with a heterogeneous peak oxygen uptake (51.9 ± 6.3 mL·min(-1)·kg(-1), range 39.7-66.2 mL·min(-1)·kg(-1)) performed an incremental ramp cycle test (20-35 W·min(-1)) to exhaustion. Breath-by-breath gas exchange was recorded, and muscle activation and oxygenation were measured with surface electromyography and near-infrared spectroscopy, respectively. The integrated electromyography (iEMG), mean power frequency (MPF), deoxygenated [hemoglobin and myoglobin] (deoxy[Hb+Mb]), and total[Hb+Mb] responses were set out as functions of work rate and fitted with a double linear function. The respiratory compensation point (RCP) was compared and correlated with the breakpoints (BPs) (as percentage of peak oxygen uptake) in muscle activation and oxygenation. The BP in total[Hb+Mb] (83.2% ± 3.0% peak oxygen uptake) preceded (P < 0.001) the BP in iEMG (86.7% ± 4.0% peak oxygen uptake) and MPF (86.3% ± 4.1% peak oxygen uptake), which in turn preceded (P < 0.01) the BP in deoxy[Hb+Mb] (88.2% ± 4.5% peak oxygen uptake) and RCP (87.4% ± 4.5% peak oxygen uptake). Furthermore, the peak oxygen uptake was significantly (P < 0.001) positively correlated to the BPs and RCP, indicating that the BPs in total[Hb+Mb] (r = 0.66; P < 0.001), deoxy[Hb+Mb] (r = 0.76; P < 0.001), iEMG (r = 0.61; P < 0.001), MPF (r = 0.63; P < 0.001), and RCP (r = 0.75; P < 0.001) occurred at a higher percentage of peak oxygen uptake in subjects with a higher peak oxygen uptake. In this study a close relationship between muscle oxygenation, activation, and pulmonary oxygen uptake was found, occurring in a cascade of events. In subjects with a higher aerobic fitness level this cascade occurred at a higher relative intensity.

The purpose of this study was to test the reliability of a new handgrip exercise protocol measuring forearm oxygenation in 20 healthy subjects on two occasions. The retest took place 48 h later and at the same time of the day. The incremental exercise consisted of 2 min steps of cyclic handgrip contraction (1/2 Hz) separated by 1 min of recovery. The exercise started at 20% MVC, was increased with 10% MVC each step and was performed until exhaustion (69.5 and 73% MVC). Near infrared spectroscopy (NIRS) was used to measure deoxygenation (deoxy[Hb + Mb]) and oxygen saturation (SmO(2)) in the forearm muscles. Prior to the exercise protocol an arterial occlusion of the forearm was performed until deoxy(Hb + Mb) did no longer increase. Maximal increase in deoxy[Hb + Mb] during 10 s of each exercise bout was expressed relative to the occlusion amplitude. ICC was used to examine the test-retest reliability. Significant ICC's were reported at 50% (r = 0.466, p = 0.017) and 60% MVC (r = 0.553, p = 0.005). The group mean of the maximum increase in oxygen extraction was 45.6 ± 16.7% and at the retest 44.9 ± 17.0% with an ICC of r = 0.867 (p < 0.001) which could be classified (Landis and Koch 1979) as almost perfect. The absolute SmO(2) values showed reliable ICC's for every submaximal intensity except at 60% MVC. An ICC of r = 0.774 (p < 0.001) was found at maximal intensity. The results of the present study show that deoxy[Hb + Mb] and SmO(2) responses during this protocol are highly reliable and indicate that this protocol could be used to get insight into deoxygenation and oxygen saturation in a population with low exercise tolerance.

The present study showed that muscle activation and oxygenation at high intensities during incremental exercise are related to pulmonary VO2 rather than external WR, with a close interrelationship between that muscle activation, oxygenation and pulmonary VO2.

Background: Impaired physical function due to muscle weakness and exercise intolerance reduces the ability to perform activities of daily living in patients with end-stage kidney disease, and by consequence, Health-Related Quality of Life (HRQoL). Furthermore, the risk of falls is an aggregate of physical function and, therefore, could be associated with HRQoL as well. The present study examined the associations between objective and subjective measures of physical function, risk of falls and HRQoL in haemodialysis patients. Methods: This cross-sectional multicentre study included patients on maintenance haemodialysis. Physical function (quadriceps force, handgrip force, Sit-to-Stand, and six-minute walking test), the risk of falls (Tinetti, FICSIT-4, and dialysis fall index) and HRQoL (PROMIS-29 and EQ-5D-3 L) were measured and analysed descriptively, by general linear models and logistic regression. Results: Of the 113 haemodialysis patients (mean age 67.5 ± 16.1, 57.5% male) enrolled, a majority had impaired quadriceps force (86.7%) and six-minute walking test (92%), and an increased risk of falls (73.5%). Whereas muscle strength and exercise capacity were associated with global HRQoL (R 2 = 0.32) and the risk of falls, the risk of falls itself was related to psycho-social domains (R 2 = 0.11) such as depression and social participation, rather than to the physical domains of HRQoL. Objective measures of physical function were not associated with subjective fatigue, nor with subjective appreciation of health status. Conclusions: More than muscle strength, lack of coordination and balance as witnessed by the risk of falls contribute to social isolation and HRQoL of haemodialysis patients. Mental fatigue was less common than expected, whereas, subjective and objective physical function were decreased.

This study aimed to determine indicators of sailing performance in 2 (age) groups of youth sailors by investigating the anthropometric, physical and motor coordination differences and factors discriminating between elite and non-elite male optimist sailors and young dynamic hikers. Anthropometric measurements from 23 optimist sailors (mean ± SD age = 12.3 ± 1.4 years) and 24 dynamic youth hikers (i.e. Laser 4.7, Laser radial and Europe sailors <18 years who have to sail the boat in a very dynamic manner, due to a high sailor to yacht weight ratio) (mean ± SD age = 16.5 ± 1.6 years) were conducted. They performed a physical fitness test battery (EUROFIT), motor coordination test battery (Körperkoordinationstest für Kinder) and the Bucket test. Both groups of sailors were divided into two subgroups (i.e. elites and non-elites) based on sailing expertise. The significant differences, taking biological maturation into account and factors discriminating between elite and non-elite optimist sailors and dynamic hikers were explored by means of multivariate analysis of covariance and discriminant analysis, respectively. The main results indicated that 100.0% of elite optimist sailors and 88.9% of elite dynamic hikers could be correctly classified by means of two motor coordination tests (i.e. side step and side jump) and Bucket test, respectively. As such, strength- and speed-oriented motor coordination and isometric knee-extension strength endurance can be identified as indicators of sailing performance in young optimist and dynamic youth sailors, respectively. Therefore, we emphasise the importance of motor coordination skill training in optimist sailors (<15 years) and maximum strength training later on (>15 years) in order to increase their isometric knee-extension strength endurance.

Objective Reduced maximal muscle strength and strength endurance have been found in patients with hypermobile Ehlers‐Danlos syndrome/hypermobility spectrum disorder (hEDS/HSD) and are recognized as common associated features of the disorder. However, the extent to which these parameters change over time is currently not documented. Therefore, the purpose of this 8‐year follow‐up study was to investigate this evolution. Methods Thirty female patients (mean age 41 years) with hEDS/HSD and 17 controls participated at baseline and 8 years later. Maximal muscle strength and strength endurance tests of the knee flexors and extensors, and 2 lower‐extremity posture maintenance tests were performed to evaluate static strength endurance. In addition, muscle mass and density were evaluated by dual‐energy x‐ray absorptiometry and peripheral quantitative computed tomography. Results Maximal muscle strength and strength endurance were significantly lower at both baseline and follow‐up in the hEDS/HSD group compared to the control group (P ≤ 0.007). Maximal muscle strength of the knee flexors (decreased in the control group: pɳ2 = 0.139), strength endurance of the knee extensors (decreased in the hEDS/HSD group and increased in the control group: pɳ2 = 0.244), and muscle density (decreased in the hEDS/HSD group: pɳ2 = 0.263) showed a significantly different evolution over 8 years. No other significant differences in evolution were found. Conclusion Decreased muscle strength was identified at both time points in patients with hEDS/HSD. The evolution of most muscle strength parameters over time did not significantly differ between groups. Future studies should focus on the effectiveness of different types of muscle training strategies in hEDS/HSD patients.