We hypothesized that high-intensity interval training (HIIT) would be more effective than moderate-intensity continuous training (MICT) at improving endothelial function and maximum oxygen uptake (V̇o_{2 max}) in obese adults. Eighteen participants [35.1 ± 8.1 (SD) yr; body mass index = 36.0 ± 5.0 kg/m²] were randomized to 8 wk (3 sessions/wk) of either HIIT [10 × 1 min, 90-95% maximum heart rate (HR_max), 1-min active recovery] or MICT (30 min, 70–75% HR_max). Brachial artery flow-mediated dilation (FMD) increased after HIIT (5.13 ± 2.80% vs. 8.98 ± 2.86%, P = 0.02) but not after MICT (5.23 ± 2.82% vs. 3.05 ± 2.76%, P = 0.16). Resting artery diameter increased after MICT (3.68 ± 0.58 mm vs. 3.86 ± 0.58 mm, P = 0.02) but not after HIIT (4.04 ± 0.70 mm vs. 4.09 ± 0.70 mm; P = 0.63). There was a significant (P = 0.02) group × time interaction in low flow-mediated constriction (L-FMC) between MICT (0.63 ± 2.00% vs. −2.79 ± 3.20%; P = 0.03) and HIIT (−1.04 ± 4.09% vs. 1.74 ± 3.46%; P = 0.29). V̇o_{2 max} increased (P < 0.01) similarly after HIIT (2.19 ± 0.65 l/min vs. 2.64 ± 0.88 l/min) and MICT (2.24 ± 0.48 l/min vs. 2.55 ± 0.61 l/min). Biomarkers of cardiovascular risk and endothelial function were unchanged. HIIT and MICT produced different vascular adaptations in obese adults, with HIIT improving FMD and MICT increasing resting artery diameter and enhancing L-FMC. HIIT required 27.5% less total exercise time and ∼25% less energy expenditure than MICT.

We examined the effects of interrupting prolonged sitting with multiple 2-min walking breaks or one 30-min continuous walking session on glucose control and ambulatory blood pressure (ABP). Ten overweight/obese, physically inactive participants (5 men; 32±5 y, BMI 30.3±4.6 kg·m-2) participated in this randomized four-trial crossover study, with each trial performed on a separate, simulated workday lasting 9h: 1) 30 min of continuous walking at 71±4% HRmax (30min-MOD); 2) 21x2-min bouts of moderate-intensity walking at 53±5% HRmax (2min-MOD), each performed every 20 min (42 min total); 3) 8x2-min bouts of vigorous-intensity walking at 79±4% HRmax (2min-VIG), each performed every h (16 min total); 4) 9h of prolonged sitting (SIT). Participants underwent continuous interstitial glucose monitoring and ABP monitoring during and after the simulated workday spent in the laboratory, with primary data analysis from 12:30 h to 07:00 h the next morning. Compared with SIT (5.6±1.1 mmol·L-1), mean 18.7-h glucose was lower during the 2min-MOD (5.2±1.1 mmol·L-1) and 2min-VIG (5.4±0.9 mmol·L-1) trials and mean 18.7-h glucose during the 30min-MOD trial (5.1±0.8 mmol·L-1) was lower than all other trials (P<0.001). Postprandial glucose was ~7-13% lower during all trials compared to SIT (P<0.001), with 30min-MOD having the greatest effect. Only the 30min-MOD trial was effective in reducing systolic ABP from 12:30 – 07:00 h (119±15 mmHg) when compared to SIT (122±16 mmHg; P<0.05). Replacing sitting with 2 min of moderate-intensity walking every 20 min or 2 min of vigorous-intensity walking every h during a simulated workday reduced 18.7-h and postprandial glucose, but only 30 min of continuous moderate-intensity walking was effective for reducing both glucose and systolic ABP.

We determined the oxygen uptake (V[Combining Dot Above]O2), heart rate (HR), and blood lactate responses to 2 high-intensity interval exercise protocols differing in interval length. On separate days, 14 recreationally active males performed a 4 × 4 (four 4-minute intervals at 90-95% HRpeak, separated by 3-minute recovery at 50 W) and 16 × 1 (sixteen 1-minute intervals at 90-95% HRpeak, separated by 1-minute recovery at 50 W) protocol on a cycle ergometer. The 4 × 4 elicited a higher mean V[Combining Dot Above]O2 (2.44 ± 0.4 vs. 2.36 ± 0.4 L·min) and "peak" V[Combining Dot Above]O2 (90-99% vs. 76-85% V[Combining Dot Above]O2peak) and HR (95-98% HRpeak vs. 81-95% HRpeak) during the high-intensity intervals. Average power maintained was higher for the 16 × 1 (241 ± 45 vs. 204 ± 37 W), and recovery interval V[Combining Dot Above]O2 and HR were higher during the 16 × 1. No differences were observed for blood lactate concentrations at the midpoint (12.1 ± 2.2 vs. 10.8 ± 3.1 mmol·L) and end (10.6 ± 1.5 vs. 10.6 ± 2.4 mmol·L) of the protocols or ratings of perceived exertion (7.0 ± 1.6 vs. 7.0 ± 1.4) and Physical Activity Enjoyment Scale scores (91 ± 15 vs. 93 ± 12). Despite a 4-fold difference in interval duration that produced greater between-interval transitions in V[Combining Dot Above]O2 and HR and slightly higher mean V[Combining Dot Above]O2 during the 4 × 4, mean HR during each protocol was the same, and both protocols were rated similarly for perceived exertion and enjoyment. The major difference was that power output had to be reduced during the 4 × 4 protocol to maintain the desired HR.

Young adults (age: 24.6 ± 3.7 years) completed 4 randomly assigned experimental conditions: (a) control, (b) 30-minute steady-state exercise (SSE) at 75–80% maximum heart rate (HRmax), (4) aerobic interval exercise (AIE): four 4-minute bouts at 90–95% HRmax, separated by 3 minutes of active recovery, and (d) sprint interval exercise (SIE): six 30-second Wingate sprints, separated by 4 minutes of active recovery. Exercise was performed on a cycle ergometer. Blood pressure (BP) was measured before exercise and every 15-minute postexercise for 3 hours. Linear mixed models were used to compare BP between trials. During the 3-hour postexercise, systolic BP (SBP) was lower (p < 0.001) after AIE (118 ± 10 mm Hg), SSE (121 ± 10 mm Hg), and SIE (121 ± 11 mm Hg) compared with control (124 ± 8 mm Hg). Diastolic BP (DBP) was also lower (p < 0.001) after AIE (66 ± 7 mm Hg), SSE (69 ± 6 mm Hg), and SIE (68 ± 8 mm Hg) compared with control (71 ± 7 mm Hg). Only AIE resulted in sustained (>2 hours) PEH, with SBP (120 ± 9 mm Hg) and DBP (68 ± 7 mm Hg) during the third-hour postexercise being lower (p ≤ 0.05) than control (124 ± 8 and 70 ± 7 mm Hg). Although all exercise bouts produced similar reductions in BP at 1-hour postexercise, the duration of PEH was greatest after AIE....

Percentile = 57.5 ± 23.2) and nine obese (body mass index percentile = 97.9 ± 1.4) children completed a two-test protocol that included an incremental test followed 15 min later by a supramaximal constant-load verification test. Results The V˙O2max achieved in verification testing (nonobese = 1.71 ± 0.31 L·min−1 and obese = 1.94 ± 0.47 L·min−1) was significantly higher than that achieved during the incremental test (nonobese = 1.57 ± 0.27 L·min−1 and obese = 1.84 ± 0.48 L·min−1; P < 0.001). There was no significant group (i.e., nonobese vs obese)–test (i.e., incremental vs verification) interaction, suggesting that there was no effect of obesity on the difference between verification and incremental V˙O2max (P = 0.747). Conclusion A verification test yielded significantly higher values of V˙O2max when compared with the incremental test in obese children. Similar results were observed in nonobese children. Supramaximal constant-load verification is a time-efficient and well-tolerated method for identifying the highest V˙O2 in nonobese and obese children....

A constant-load exercise bout to exhaustion after a graded exercise test to verify maximal oxygen uptake (V[Combining Dot Above]O2max) during cycle ergometry has not been evaluated in sedentary adults with obesity. Nineteen sedentary men (n = 10) and women (n = 9) with obesity (age = 35.8 ± 8.6 years; body mass index [BMI] = 35.9 ± 5.1 kg·m; body fat percentage = 44.9 ± 7.2) performed a ramp-style maximal exercise test (ramp), followed by 5-10 minutes of active recovery, and then performed a constant-load exercise bout to exhaustion (verification test) on a cycle ergometer for determination of V[Combining Dot Above]O2max and maximal heart rate (HRmax). V[Combining Dot Above]O2max did not differ between tests (ramp: 2.29 ± 0.71 L·min, verification: 2.34 ± 0.67 L·min; p = 0.38). Maximal heart rate was higher on the verification test (177 ± 13 b·min vs. 174 ± 16 b·min; p = 0.03). Thirteen subjects achieved a V[Combining Dot Above]O2max during the verification test that was ≥2% (range: 2.0-21.0%; 0.04-0.47 L·min) higher than during the ramp test, and 8 subjects achieved a HRmax during the verification test that was 4-14 b·min higher than during the ramp test. Duration of verification or ramp tests did not affect V[Combining Dot Above]O2max results, but the difference in HRmax between the tests was inversely correlated with ramp test duration (r = -0.57, p = 0.01). For both V[Combining Dot Above]O2max and HRmax, differences between ramp and verification tests were not correlated with BMI or body fat percentage. A verification test may be useful for identifying the highest V[Combining Dot Above]O2max and HRmax during cycle ergometry in sedentary adults with obesity.