The physiology behind exercise testing

Body composition influences blood pressure during submaximal graded test in women

This study aimed to determine whether body composition affected cardiovascular responses of normal, overweight and obese women by comparing heart rate (HR) and blood pressure (BP) during a graded submaximal treadmill exercise. Thirty five healthy non-smoking, premenopausal women (age 30.8 ± 9.5 yr; height 1.66 ± 0.05 m; weight 73.8 ± 18.9 kg; body fat 36.2 ± 9.5%; maximum oxygen uptake 33.5 ± 8.1 mL·min·kg^-1) volunteered for this study, and were classified into three groups based on BMI: normal weight (NOR; ≤24.9 kg·m²), overweight (OVW; 25-29.9 kg·m²) and obese (OBE; ≥30 kg·m²). Participants performed a submaximal graded test at 30%, 40%, 50% and 60% of maximal oxygen uptake, during which HR, systolic BP (SBP), diastolic BP (DBP) and mean arterial pressure (MAP) were measured. At rest, participants of OBE group had higher BP than NOR and OVW. During the submaximal graded test, HR, SBP and MAP increased as a function of intensity. There were no group differences in HR, but greater SBP, DBP and MAP in OBE compared to NOR and OBW at all intensities except 60%. Overall, our study further contributes to underscore the importance of stress testing specifically to evaluate the increased risks apparently healthy obese women are placed at to developing diseases from the chronic exposure to raised BP, despite normal resting BP and HR responses during exercise.

Neuromuscular, hormonal and cardiovascular adaptations to eight-week HIIT and continuous aerobic training combined with neuromuscular electrical stimulation

BACKGROUND

Whether high-or-low intensity exercise coupled with neuromuscular electrostimulation (NMES) affect IGF-1 and IGFBP-1 is unknown. The scope of this study was to test whether 8-week high-intensity interval training (HIIT) and continuous aerobic training (CA) combined with/without NMES performed at 65% and 120% of VO2max on a cycle ergometer induce different metabolic adaptations.

METHODS

A randomized controlled trial with a parallel groups study design was used. Thirty healthy untrained male participants (age: 21.33±1.24 years, height: 177.80±5.97 cm, weight: 73.74±7.90 kg, lean body mass: 64.29±5.11 kg, percent body fat: 12.43±5.34%) voluntarily participated in this study. Six participants were allocated to Control, six to HIIT, six to HIIT+NMES, six to CA, and six to CA+NMES.

RESULTS

Pre- to post-test IVO2max, blood lactate concentrations, O2 kinetics, peak torques at 60o/s and 180o/s were found statistically significant (P<0.05, P<0.001). IGF-1 pre 15 min in CA and IGF-1 post 30 min in HIIT group was found significantly higher compared to control group (16.93±8.40 vs. 6.05±4.25, P=0.024; 10.80±3.94 vs. 6.15±2.56, P=0.037), respectively. Additionally, IGFBP-1 were found significantly higher in CA+NMES group than HIIT group (0.95±0.67 vs. 1.23±0.56). Eight week post IGF-1/IGFBP-1 ratios were found higher in pre 15 min, post 30 min and post 24 h compared to baseline pre 15 min, post 30 min and post 24 h measurements in all groups (8.92±4.72 vs. 3.93±3.14; 9.41±3.72 vs. 3.99±1.76; 8.63±3.01 vs. 5.89±3.01, respectively). Also, IGFBP-1 post 30 min was significantly lower in HIIT+NMES while CA group showed significantly lower baseline and 24 h post IGFBP-1 compared to pre-test measurements (Z=-3.20, P=0.001; Z=-3.72, P=0.000; Z=-2.93, P=0.000).

CONCLUSIONS

HIIT and CA training induce different stimuli on IGF-1 and IGFBP-1 and NMES application combined with high-and-low intensity exercise is highly effective in improving athletic performance.

Physiological differences between a noncontinuous and a continuous endurance training protocol in recreational runners and metabolic demand prediction

This study investigated the physiological difference in recreational runners between a noncontinuous and a continuous endurance training protocol. It also aimed to determine physiological surrogate that could monitor metabolic demand of prolonged running in real‐time. For data collection, a total of 18 active male recreational runners were recruited. Physiological (HR, RR, RER, ṼO₂, BLa), and overall perceptual (RPE_O) responses were recorded against three designed test sessions. Session 1 included ṼO_2submax test to determine critical speed (CS) at anaerobic threshold (AT). Session 2 was the noncontinuous CS test until exhaustion, having 4:1 min work‐to‐rest ratio at CS, whereas session 3 was the continuous CS test till exhaustion. As 1‐min recovery during session 2 may change fatigue behavior, it was hypothesized that it will significantly change the physiological stress and hence endurance outcomes. Results reported average time to exhaustion (TTE) was 37.33(9.8) mins for session 2 and 23.28(9.87) mins for session 3. Participants experienced relatively higher metabolic demand (BLa) 6.78(1.43) mmol.l⁻¹ in session 3 as compared to session 2 (5.52(0.93) mmol.l⁻¹). RER was observed to increase in session 3 and decrease in session 2. Student's paired t‐test only reported a significant difference in TTE, ṼO₂, RER, RPE_O, and BLa at “End” between session 2 and 3. Reported difference in RPE_O and %HR_max at “AT” were 5 (2.2) and 89.8 (2.60)% during session 2 and 6 (2.5) and 89.8 (2.59)% during session 3, respectively. Regression analysis reported strong correlation of %HR_max (adj. R‐square = 0.588) with BLa than RPE_O (adj. R‐square = 0.541). The summary of findings suggests that decreasing RER increased TTE and reduced BLa toward “End” during session 2 which might have helped to have better endurance. The %HR_max was identified to be used as a better noninvasive surrogate of endurance intensity estimator.