Low physical activity is a risk factor for cardiovascular disease (CVD) and all-cause morbidity and mortality. CVD alters heart rate variability (HRV). Interestingly, HRV can improve after exercise ...training. Therefore, this study aimed to examine the effect of whole-body high-intensity interval training (whole-body HIIT) on HRV in low physical activity adults.
Twenty-one low physical activity young adults were randomly assigned into two groups: whole-body HIIT (n = 10, females = 2/males = 8, age 22 ± 0.8 years, BMI 19.5 ± 1.0 kg/m2) and control (n = 11, females = 4/males = 7, age 21.7 ± 0.8 years, BMI 19.8 ± 0.9 kg/m2). A 6-week exercise program (3 days per week) consisting of 10 min of whole-body HIIT (burpees, mountain climbers, jumping jacks, and squats) at their maximal effort was administered. Baseline and post-training HRV (time domain: SDNN and RMSSD, frequency domain: LF, HF, and LF/HF ratio) and resting heart rate (HRrest) were recorded.
The time domain parameter increased significantly in the whole-body HIIT group (SDNN; 50.95 ± 37.17 vs. 73.40 ± 40.70 ms, p < 0.05, RMSSD; 54.45 ± 56.04 vs. 81.26 ± 60.14 ms, p < 0.05). HRrest decreased significantly following training (73.94 ± 13.2 vs. 66.1 ± 10.8 bpm, p < 0.05). However, there were no significant differences in all frequency-domain parameters.
Six weeks of whole-body HIIT improved cardiovascular autonomic function in insufficiently active adults. Thus, whole-body HIIT might be considered an alternative exercise for reducing the risk of CVD.
Reduced-exertion high-intensity interval training (REHIT) is a genuinely time-efficient intervention that can improve aerobic capacity and insulin sensitivity in sedentary individuals. The present ...study compared the effects of REHIT and moderate-intensity walking on health markers in patients with type 2 diabetes (T2D) in a counter-balanced crossover study. Sixteen men with T2D (mean ± SD age: 55 ± 5 years, body mass index: 30.6 ± 2.8 kg·m
−2
, maximal aerobic capacity: 27 ± 4 mL·kg
−1
·min
−1
) completed 8 weeks of REHIT (three 10-min low-intensity cycling sessions/week with two “all-out” 10–20-s sprints) and 8 weeks of moderate-intensity walking (five 30-min sessions/week at an intensity corresponding to 40%–55% of heart-rate reserve), with a 2-month wash-out period between interventions. Before and after each intervention, participants underwent an incremental fitness test, an oral glucose tolerance test (OGTT), a whole-body dual-energy X-ray absorptiometry scan, and continuous glucose monitoring. REHIT was associated with a significantly larger increase in maximal aerobic capacity compared with walking (7% vs. 1%; time × intervention interaction effect: p < 0.05). Both REHIT and walking decreased resting mean arterial pressure (−4%; main effect of time: p < 0.05) and plasma fructosamine (−5%; main effect of time: p < 0.05). Neither intervention significantly improved OGTT-derived measures of insulin sensitivity, glycaemic control measured using continuous glucose monitors, blood lipid profile, or body composition. We conclude that REHIT is superior to a 5-fold larger volume of moderate-intensity walking in improving aerobic fitness, but similar to walking REHIT is not an effective intervention for improving insulin sensitivity or glycaemic control in T2D patients in the short term.
Virtual reality (VR) exercises are reportedly beneficial as a physical activity tool for health promotion and rehabilitation, and can also help individuals exercise under professional supervision. We ...developed and investigated the potential feasibility of a VR-based aerobic exercise program using the XBOX ONE console and Kinect sensor with real-time pulse rate monitoring. The VR setting consisted of two-dimensional (2D) environments via computer, laptop, or television screens. In addition, the study investigated the potential feasibility of the VR-based exercise program on hemodynamic response and arterial stiffness in healthy participants of various ages.
Healthy participants (
= 30) aged > 18 years were enrolled in the VR exercise-based program. All participants were required to wear a polar heart rate (HR) monitor set for moderate-intensity exercise, targeting 40%-59% of their HR reserve. Hemodynamic and arterial stiffness (pulse wave velocity) were noninvasively measured. The Borg scale rate of perceived exertion (RPE) was also assessed.
Following a VR-guided exercise routine, all participants performed moderate-intensity exercise with no adverse health outcomes during or after the exercise. The effects of VR-based aerobic exercise extended beyond enhanced central hemodynamic and arterial stiffness. However, neither hemodynamic nor arterial stiffness showed significant differences before and after the VR exercise, except for a higher RPE response following the exercise program.
VR-based aerobic exercise with pulse rate monitoring is a promising physical activity tool to induce physiological changes and impact dyspnea scales and is also feasible for administration to healthy populations.
Background and Purpose
Pulmonary dysfunction and inspiratory muscle weakness are frequently observed after cardiac surgery. Understanding the load on and capacity of respiratory muscles can provide ...valuable insights into the overall respiratory mechanics and neural regulation of breathing. This study aimed to assess the extent of neural respiratory drive (NRD) and determine whether admission‐to‐discharge differences in NRD were associated with inspiratory muscle strength changes among patients undergoing open‐heart surgery.
Methods
This cross‐sectional study was conducted on 45 patients scheduled for coronary artery bypass graft or heart valve surgery. NRD was measured using a surface parasternal intercostal electromyogram during resting breathing (sEMGpara tidal) and maximal inspiratory effort (sEMGpara max). Maximal inspiratory pressure (MIP) was used to determine inspiratory muscle strength. Evaluations were performed on the day of admission and discharge.
Results
There was a significant increase in sEMGpara tidal (6.9 ± 3.6 μV, p < 0.001), sEMGpara %max (13.7 ± 11.2%, p = 0.008), and neural respiratory drive index (NRDI, the product of EMGpara %max and respiratory rate) (337.7 ± 286.8%.breaths/min, p < 0.001), while sEMGpara max (−43.6 ± 20.4 μV, p < 0.01) and MIP (−24.4 ± 10.7, p < 0.001) significantly decreased during the discharge period. Differences in sEMGpara tidal (r = −0.369, p = 0.045), sEMGpara %max (r = −0.646, p = 0.001), and NRDI (r = −0.639, p = 0.001) were significantly associated with a reduction in MIP.
Discussion
The findings indicate that NRD increases after open‐heart surgery, which corresponds to a decrease in inspiratory muscle strength.
Non-communicable diseases (NCDs) are the leading cause of death worldwide. Physical inactivity is a risk factor of NCDs. Although exercise recommendations have been made, many people do not meet ...these criteria. Lack of time is one of the main perceived exercise barriers. To address this barrier, more time-efficient exercise protocols have been developed. One of these is Reduced-Exertion High-Intensity Interval Training (REHIT), which comprises two repeated 20-s 'all-out' sprints within a 10-minute protocol. Health benefits from REHIT have been demonstrated; e.g. REHIT improves V̇O2max and insulin sensitivity in healthy individuals. However, no studies have examined whether the REHIT protocol can be modified to make it either shorter or easier, without affecting the beneficial changes in V̇O2max. The effects of REHIT on V̇O2max in different participants still require investigation, and the mechanisms of the increase in V̇O2max remain unclear. Therefore, the aims of this thesis were to optimise the REHIT protocol to be a time-efficient and effective protocol for improved V̇O2max, to investigate the mechanisms underlying the improvement in V̇O2max after REHIT, and to examine the effect of REHIT on V̇O2max in type 2 diabetes (T2D) patients. Reducing the number of sprint repetitions (Chapter 2) and sprint duration (Chapter 3) attenuated the improvements in V̇O2max with REHIT, but training fewer sessions per week (Chapter 4) did not attenuate the improvements in V̇O2max. Importantly, the affective responses associated with REHIT are similar when compared with current exercise recommendations (Chapter 5). V̇O2max increases but insulin sensitivity does not change following REHIT in T2D patients (Chapter 6). Despite glycogen depletion using a protocol with single sprints, no changes in serum levels of the myokine SPARC nor V̇O2max were observed, so no information on possible mechanisms could be drawn from this thesis. Overall, it can be concluded that a manageable, effective and time-efficient exercise protocol for improving V̇O2max is REHIT, consisting of two 20-s 'all-out' cycle sprints within a 10-minute session performed at least two times per week.
We have previously demonstrated that reduced-exertion high-intensity interval training (REHIT) is a genuinely time-efficient exercise strategy for improving cardiometabolic health. Here, we examined ...the affective and perceptual responses to REHIT. Eight young men and women (age 21 ± 1 y, BMI 24.9 ± 2.1 m/kg
2
, V̇O
2
max 39 ± 10 ml/kg/min) and 11 men with type 2 diabetes (T2D; age 52 ± 6 y, BMI 29.7 ± 3.1 m/kg
2
, V̇O
2
max 29 ± 5 ml/kg/min) took part in three-arm crossover trials with RPE and affective valence measured during, and enjoyment and exercise preferences measured following either: 1) REHIT (2 × 20-s sprints in a 10-min exercise session), 2) HIIT (10 × 1-min efforts) and 3) 30 min MICT. Furthermore, 19 young men and women (age 25 ± 6 y, BMI 24 ± 4 m/kg
2
, V̇O
2
max 34 ± 8 ml/kg/min) completed a 6-week REHIT intervention with affective valence during an acute REHIT session measured before and after training. Affect decreases (briefly) during REHIT, but recovers rapidly, and the decline is not significantly different when compared to MICT or HIIT in either healthy participants or T2D patients. Young sedentary participants reported similar levels of enjoyment for REHIT, MICT and HIIT, but 7 out of 8 had a preference for REHIT. Conversely, T2D patients tended to report lower levels of enjoyment with REHIT compared with MICT. The decrease in affective valence observed during an acute REHIT session was significantly attenuated following training. We conclude that affective and perceptual responses to REHIT are no more negative compared to those associated with MICT or HIIT, refuting claims that supramaximal sprint interval training protocols are associated with inherent negative responses.
In the present randomised-controlled trial we investigated the effect of reduced-exertion high-intensity interval training (REHIT) training frequency (2, 3, or 4 sessions/week for 6 weeks) on maximal ...aerobic capacity in 42 inactive individuals (13 women; mean ± SD age: 25 ± 5 years, maximal aerobic capacity: 35 ± 5 mL·kg
−1
·min
−1
). Changes in maximal aerobic capacity were not significantly different between the 3 groups (2 sessions/week: +10.2%; 3 sessions/week: +8.1%; 4 sessions per week: +7.3%). In conclusion, a training frequency of 2 sessions/week is sufficient for REHIT to improve maximal aerobic capacity.
Novelty
We demonstrate that reducing REHIT training frequency from 3 or 4 to 2 sessions/week does not attenuate improvements in the key health marker of maximal aerobic capacity.
Recent studies have demonstrated that modifying the “classic” 6 × 30-s “all-out” sprint interval training protocol by incorporating either shorter sprints (6 × 10-s or 15-s sprints) or fewer sprints ...(e.g., 2 × 20-s sprints; reduced-exertion high-intensity interval training (REHIT)) does not attenuate the training-induced improvements in maximal aerobic capacity. The aim of the present study was to determine if reducing the sprint duration in the REHIT protocol from 20 s to 10 s per sprint influences acute affective responses and the change in maximal aerobic capacity following training. Thirty-six sedentary or recreationally active participants (17 women; mean ± SD; age: 22 ± 3 years; body mass index: 24.5 ± 4.6 kg·m
−2
; maximal aerobic capacity: 37 ± 8 mL·kg
−1
·min
−1
) were randomised to a group performing a “standard” REHIT protocol involving 2 × 20-s sprints or a group who performed 2 × 10-s sprints. Maximal aerobic capacity was determined before and after 6 weeks of 3 weekly training sessions. Acute affective responses and perceived exertion were assessed during training. Greater increases in maximal aerobic capacity were observed for the group performing 20-s sprints (2.77 ± 0.75 to 3.04 ± 0.75 L·min
−1
; +10%) compared with the group performing 10-s sprints (2.58 ± 0.57 vs. 2.67 ± 3.04 L·min
−1
; +4%; group × time interaction effect: p < 0.05; d = 1.06). Positive affect and the mood state vigour increased postexercise, while tension, depression, and total mood disturbance decreased, and negative affect remained unchanged. Affective responses and perceived exertion were not altered by training and were not different between groups. In conclusion, reducing sprint duration in the REHIT protocol from 20 s to 10 s attenuates improvements in maximal aerobic capacity, and does not result in more positive affective responses or lower perceived exertion.
Myokines may play a role in the health benefits of regular physical activity. Secreted protein acidic rich in cysteine (SPARC) is a pleiotropic myokine that has been shown to be released into the ...bloodstream by skeletal muscle in response to aerobic exercise. As there is evidence suggesting that SPARC release may be linked to glycogen breakdown and activation of 5' adenosine monophosphate-activated protein kinase, we hypothesised that brief supramaximal exercise may also be associated with increased serum SPARC levels. In the present study, 10 participants (3 women; mean ± SD age: 21 ± 3 y, body mass index (BMI): 22 ± 3 kg m
, and V˙O
: 39 ± 6 mL kg
min
) performed an acute bout of supramaximal cycle exercise (20-s Wingate sprint against 7.5% of body mass, with a 1-min warm-up and a 3-min cool-down consisting of unloaded cycling). Serum SPARC levels were determined pre-exercise as well as 0, 15, and 60 min post-exercise and corrected for plasma volume change. To determine whether regular exercise affected the acute SPARC response, participants repeated the acute exercise protocol three times per week for four weeks, and serum SPARC response to supramaximal exercise was reassessed after this period. Acute supramaximal exercise significantly decreased plasma volume (-10%; p < .001), but was not associated with a significant change in serum SPARC levels at either the pre-training or post-training testing sessions. In conclusion, in contrast to aerobic exercise, a single brief supramaximal cycle sprint is not associated with an increase in serum SPARC levels, suggesting that SPARC release is not related to skeletal muscle glycogen breakdown.
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