Metabolic Effects of 6 Weeks of Sprint Interval Training with Virtual Supervision in Persons with Obesity

To evaluate the metabolic effects of 6 weeks of Sprint Interval Training under virtual supervision with no equipment in individuals with obesity.

Thirteen volunteers with obesity (8 men, age 29±5, BMI 36.55±4.93) participated in the study. During a laboratory visit, their basal metabolic rate and fat oxidation were assessed using indirect calorimetry. First, a rest indirect calorimetry in the supine position for 20 min was taken for Resting metabolic rate (RMR). Then, an incremental exercise protocol on a cycle ergometer was performed to determine maximum fat oxidation (MFO), intensity at MFO (Fatmax), and VO₂max. The previous validated protocol consisted of two phases: the first was to determine MFO through 3-minute steps with 15W increments at a cadence of 60rpm, stopping when the respiratory quotient ≥1. After a 5-minute rest, the second phase continued with 15W/min steps until exhaustion to measure VO₂max. Maximal fat oxidation was estimated by interpolating the results from the rest, incremental, and VO₂max tests. Participants then underwent a 6-week intervention of SIT, performing 3 sessions per week. Each session involved 3 bouts of all-out high knee running in place for 20 seconds, with 3-minute rests between bouts, supervised via video conference by senior Physical Therapy students. Heart rate, perceived exertion, and incidence of events were recorded for each session. Initial tests were repeated after the intervention, and data were analyzed using paired t-tests with a 95% confidence interval. Results are reported as means and standard deviations.

One participant withdrew due to muscular discomfort; no incidents occurred during the training sessions. Twelve participant's data were analyzed. No significant change was shown from RMR with 2284±546.6 kcal/day values to 2267±407.5 kcal/day (p=0.905). MFO increased slightly, from 0.230±0.1 g/min to 0.239±0.088 g/min (p=0.776), while Fatmax rose from 39.8±0.12% to 40.4±0.06% (p=0.890). A significant improvement was observed in VO₂max, increasing from 26.11±5.65 to 27.39±5.62 ml/min/kg (p=0.024).

When properly supervised, SIT is a safe and effective method for improving VO₂max in individuals with obesity. However, the protocol did not provide sufficient volume or intensity to increase RMR or MFO significantly.

Low-volume SIT supervised virtually and requiring no equipment, can serve as a practical initial exercise intervention for individuals with obesity, given its minimal need for evaluation and time commitment.