Writing in the Journal of the International Society of Sports, the researchers noted that although HIIT improved exercise tolerance in obese women, it may also increase waist size. Concurrent supplementation with Lactiplantibacillus plantarum TWK10, however, mitigated these negative outcomes and improved hip circumference.
The data also indicated that HIIT plus TWK10 could improve markers of exercise tolerance such as time to exhaustion (TTE)
“HIIT improves TTE but negatively affects waist circumference compared to the control group,” the researchers concluded.
“However, when combined with probiotics, the probiotics not only help enhance TTE but also counteract the negative impact on waist circumference and further reduce hip circumference, resulting in a synergistic effect.”
Why could HIIT have negative effects?
While the benefits of HIIT are well recognized, animal studies suggest that acute vigorous exercise reduces subsequent physical activity and body temperature and may lead to weight gain.
The authors of the new paper speculated that the winter months (in which the study occurred) cause greater weight gain due to lower temperatures stimulating the appetite-promoting hormone ghrelin. Furthermore, colder temperatures may increase the amount people eat following exercise.
These reasons may explain some of the negative impacts of the interventions “offsetting the benefits of HIIT in reducing body weight and even increasing waist circumference in the present study,” they wrote.
Additionally, previous studies indicate that HIIT positively affects body composition after 12 weeks, therefore a longer study period might be required to see the benefits.
The current study suggests that probiotics may mitigate the adverse effects of HIIT in colder seasons, noting that L. plantarum TWK10 has previously been associated with weight control.
Study details
The placebo-controlled, double-blind trial recruited 47 obese women between the ages of 35 and 55 with a body fat percentage of over 35% and assigned them to one of four groups: probiotics, HIIT, HIIT with probiotics and a control group.
Participants in the probiotics groups took 60 billion CFUs per day of TWK10, and the exercise groups did three weekly sessions of HIIT for eight weeks. Sessions consisted of running at 85% to 90% velocity at VO2max for two minutes, followed by a minute inactive rest interval, repeated for seven cycles.
Researchers assessed anthropometry, cardiorespiratory endurance, blood glucose and lipid profile at baseline and the end of the trial.
The HIIT group’s waist size increased significantly compared to the control and probiotic-only groups, but there was no significant waist difference between the HIIT with probiotics and control groups.
Conversely, the HP hip circumference decreased significantly than in the other groups. There was a greater increase in time to exhaustion (TTE) rates in the HIIT and HIIT with probiotics groups than in the control group.
The study also noted that HIIT increased fasting blood glucose (FBG), which contradicts previous research. The researchers hypothesized that this may be due to an inflammatory response, which may be offset with probiotics, but that the causal relationship is unclear.
They noted the study’s limitations and called for further research that considers time of year and menstrual status, which may affect results.
Source: Journal of the International Society of Sports Nutrition
21(1) doi: 10.1080/15502783.2024.2425609
“Effects of probiotic supplementation with high-intensity interval training on cardiorespiratory endurance and metabolism in Middle-Aged Obese Women.”
Authors: Y.C. Chen et al.
