Impact of Concussion History on Heart Rate Variability during Bouts of Acute Stress

Context: Following a sports-related concussion, many athletes experience persisting neurophysiological alterations. These alterations may be absent at rest but emerge during moments of physiological stress. Unnoticed and untreated neurophysiological dysfunction may negatively impact long-term neurological health in adolescent athletes as they are at a critical point in development. Objective: To assess cardio-autonomic functioning in athletes with and without a history of concussion by quantifying measures of heart rate variability (HRV) during times of physical and mental exertion. Design: Case-control study. Setting: Research laboratory Patients or Other Participants: Thirty-four male midget-AAA hockey players were separated into those with (n = 16, age = 16.1 ± 1 years, BMI = 23.3 ± 1.8) and those without (n = 18, age = 16.0 ±1 years, BMI = 23.6 ± 2.5) a history of concussion. Intervention(s): All athletes completed a series of HRV recording sessions: 1) at rest; 2) while completing a cognitive task at rest; and 3) while completing a cognitive task after a bout of submaximal aerobic exercise. Main Outcome Measure(s): Time-domain measures of HRV; mean NN interval (NN), standard deviation of NN interval (SDNN), and root mean square of successive differences (RMSSD) were quantified for each assessment. Results: Analyses revealed no demographic differences between groups. No between-group differences in HRV at rest, were observed. However, during completion of the cognitive task at rest and following aerobic exercise, athletes with a history of concussion demonstrated significantly higher SDNN (63.2 ± 4.1 vs. 78.1 ± 4.3; 65.2 ± 3.8 vs 71.2 ± 4.3, p = 0.046) and RMSSD (59.0 ± 5.6 vs. 75.8 ± 6.0; 59.0 ± 5.2 vs. 74.0 ± 5.5, p = 0.035). Conclusion: The results suggest concussive injuries may result in long-term cardio-autonomic dysfunction. Furthermore, these deficits may not be present at rest but may be triggered by physiological stress.

Metabolic Differences During Submaximal, Steady-State Aerobic Exercise between Sarcopenic and Non-Sarcopenic Older Adults

Objectives To examine differences in metabolic flexibility during submaximal aerobic exercise in sarcopenic (S) and non-sarcopenic (NS) older adults. Methods Twenty-two older adults (mean age ± SE = 77 ± 2) were categorized as NS (n = 11) and S (n = 11) based on grip strength and muscle mass. Participants completed an aerobic, steady-state 10-min walk on a treadmill at 50 – 60% of their estimated V̇O2 max. Indirect calorimetry was assessed at baseline (fasted) and during the treadmill test to analyze respiratory quotient (RQ), carbohydrate (CHO) oxidation and fat oxidation, and % contributions of CHO and fat oxidation to energy expenditure (%CHO and %FAT, respectively). Two-way mixed factorial ANOVAS (time x group) and follow up t-tests were used to examine between group differences. Results At baseline, RQ was higher (0.76 ± 0.01 vs. 0.72 ± 0.01, p = 0.025) and fat oxidation was lower (0.08 ± 0.01 vs. 0.11 ± 0.01 g · min−1, p = 0.003) in S than NS individuals. The S group had significantly greater %CHO versus %FAT from 6 – 10 min of exercise (p = 0.005–0.014), whereas NS individuals maintained an approximately equal distribution of %CHO and %FAT until 8 – 10 min (p = 0.034–0.047). RQ (0.90 ± 0.06 vs. 0.86 ± 0.01, p = 0.039) and %CHO (70% vs. 57%, p = 0.046) were greater in S compared to NS at 8 min of exercise. Fat oxidation was consistently higher in NS than S individuals from 4 - 10 of min exercise (p = 0.016–0.045). Conclusions Since skeletal muscle utilizes a large amount of energy during exercise, metabolic flexibility is key to efficiently utilize both CHO and fat sources to generate energy to match metabolic demands. Our data reveals that NS individuals were able to rely on both fuel sources during submaximal exercise indicating metabolic flexibility. Typically, exercising at 50 – 60% V̇O2 max utilizes 50% CHO and 50% fat contributions to energy expenditure, as observed in NS individuals. On the other hand, in S individuals, CHO composed a much larger proportion of total energy usage during exercise. These findings suggest that S individuals have low metabolic flexibility with higher dependence on CHO for energy during low-moderate aerobic activity. Funding Sources This study was funded by Abbott Nutrition.

Can HRV Biofeedback Improve Short-Term Effort Recovery? Implications for Intermittent Load Sports

As intensity and physical demands continue to rise in sport competition, faster and better recovery becomes essential. The aim of this study was to assess the effects of HRV biofeedback (HRVB) while recovering from a submaximal aerobic exercise. Ten physically-active graduate students participated in the study, which was conducted in four sessions: exercise with free-breathing recovery, first resonance frequency (RF) detection, second RF detection, and exercise applying HRVB during recovery. Measurements included time spent running and recovering, HRV parameters, and recovery/exertion perceptions. The results indicate that using HRVB during recovery improves cardiac variability (RRmean, SDNN, RMSSD and LF; p < 0.01). HRVB also lowers recovery time (p < 0.05) and seems to be improving the perception of recovery (p = 0.087). Moreover, time spent exercising (p < 0.01) and perceived physical exertion (p < 0.05) were higher when applying HRVB. The improvement in the psychophysiological adaptation after intensive aerobic exercise provided by the HRVB is a valuable benefit, not only for competition-driven athletes, but also for the general population.

Similarities and dissimilarities in response to specific submaximal aerobic exercise in newcomer and well-trained athletes

The study was aimed on evaluation the applicability of certain distinct characteristics of heart rate dynamics dependence upon physical training load as criteria of young athletes functional fitness. Nine elite adult canoe and kayak rowers and twenty five young skiers aged 11-13 took part in the research program. Canoe and kayak rowers performed incremental tests on a rowing simulator (4*1000 m). The following parameters were measured: heart rate, oxygen heart rate, breath frequency, respiratory exchange ratio, oxygen uptake, and minute ventilation. Young skiers performed moderate run on a stadium track maintaining constant speed to voluntary physical exhaustion. Comparison of the trends in young and elite athletes allows assuming that the response to the given load on the third segment of the test exceeded the current level of fitness and continuation of the exercise at this level can cause overstrain and overtraining. It has to be pointed out that this assumption requires further research with measurement of a broader range of parameters.

Exercise plasma metabolomics and xenometabolomics in obese, sedentary, insulin-resistant women: impact of a fitness and weight loss intervention

Insulin resistance has wide-ranging effects on metabolism, but there are knowledge gaps regarding the tissue origins of systemic metabolite patterns and how patterns are altered by fitness and metabolic health. To address these questions, plasma metabolite patterns were determined every 5 min during exercise (30 min, ∼45% of V̇o2peak, ∼63 W) and recovery in overnight-fasted sedentary, obese, insulin-resistant women under controlled conditions of diet and physical activity. We hypothesized that improved fitness and insulin sensitivity following a ∼14-wk training and weight loss intervention would lead to fixed workload plasma metabolomics signatures reflective of metabolic health and muscle metabolism. Pattern analysis over the first 15 min of exercise, regardless of pre- versus postintervention status, highlighted anticipated increases in fatty acid tissue uptake and oxidation (e.g., reduced long-chain fatty acids), diminution of nonoxidative fates of glucose [e.g., lowered sorbitol-pathway metabolites and glycerol-3-galactoside (possible glycerolipid synthesis metabolite)], and enhanced tissue amino acid use (e.g., drops in amino acids; modest increase in urea). A novel observation was that exercise significantly increased several xenometabolites (“non-self” molecules, from microbes or foods), including benzoic acid-salicylic acid-salicylaldehyde, hexadecanol-octadecanol-dodecanol, and chlorogenic acid. In addition, many nonannotated metabolites changed with exercise. Although exercise itself strongly impacted the global metabolome, there were surprisingly few intervention-associated differences despite marked improvements in insulin sensitivity, fitness, and adiposity. These results and previously reported plasma acylcarnitine profiles support the principle that most metabolic changes during submaximal aerobic exercise are closely tethered to absolute ATP turnover rate (workload), regardless of fitness or metabolic health status.

Autonomic responses induced by aerobic submaximal exercise in obese and overweight adolescents

BackgroundGraded exercises tests are performed in adult populations; nonetheless, the use of this type of assessment is greatly understudied in overweight and obese adolescents.ObjectiveTo investigate heart rate autonomic responses to submaximal aerobic exercise in obese and overweight adolescents.MethodsWe recruited 40 adolescents divided into two groups: (1) overweight group comprising 10 boys and 10 girls between Z-score +1 and +2 and (2) obese group comprising 10 boys and 10 girls above Z-score >+2. Heart rate variability was analysed before (T1) and after exercise (T2–T4) on treadmill at a slope of 0%, with 70% of the maximal estimated heart rate (220 – age) for 20 minutes.ResultsHeart rate in the overweight group was: 93.2±10.52 bpm versus 120.8±13.49 bpm versus 94.6±11.65 bpm versus 93.0±9.23 bpm, and in the obese group was: 92.0±15.41 bpm versus 117.6±16.31 bpm versus 92.1±12.9 bpm versus 91.8±14.33 bpm. High frequency in the overweight group was: 640±633.1 ms2 versus 84±174.66 ms2 versus 603.5±655.31 ms2 versus 762.6±807.21 ms2, and in the obese group was: 628.4±779.81 ms2 versus 65.4±119.34 ms2 versus 506.2±482.70 ms2 versus 677.9±939.05 ms2; and root mean square of successive differences in the overweight group was: 37.9±18.81 ms versus 10.9±8.41 ms versus 32.8±24.07 ms versus 36.7±21.86 ms, and in the obese group was: 38.7±23.17 ms versus 11.5±8.62 ms versus 32.3±16.74 ms versus 37.3±24.21 ms. These values significantly changed during exercise compared with resting values in overweight and obese groups. Moreover, we also reported no significant difference of resting parasympathetic control of heart rate between obese and overweight adolescents.ConclusionThere was no significant difference of autonomic responses elicited by submaximal aerobic exercise between overweight and obese adolescents.

Involvement of birth weight and body composition on autonomic recovery following aerobic exercise in children: A prospective, observational and analytical study

ABSTRACTBirth weight (BW) can be used to assess the health status of the newborn. However, its impacts on later in life regarding heart rate (HR) variability (HRV) is not totally clear. We aimed to analyze the involvement of BW and body composition on HRV recovery following aerobic exercise in children. The study was conducted in healthy children 9 to 11 years of age (40 females and 27 males) divided into two groups: G1 (BW < 3400 grams, N = 33) and G2 (BW > 3400 grams, N = 34). The volunteers completed an experimental protocol of submaximal aerobic exercise on a treadmill and remained seated for 30 minutes after exercise. Systolic (SAP) and diastolic arterial pressure (DAP), respiratory rate (f) and HRV were analyzed before and during recovery from exercise. SAP and f were significantly decreased 30 minutes after exercise compared to 1 minute after exercise in G1 and G2. Mean HR, high frequency band of spectral analysis (HF), root mean square of successive interbeat intervals difference, SD1 index and mean lenght were diminished 0 to 5 minutes after exercise compared to rest in G2 while maximum lenght increased 0 to 5 minutes after exercise compared to resting in G2. Linear regression revealed association of fat percentage and BW with nonlinear HRV recovery. In conclusion, autonomic recovery after exercise was somewhat delayed in children with high BW. BW and fat percentage slightly influence HRV recovery.