Feet-heating and calf-heating have opposing effects on glucose tolerance and heart rate variability: a randomized, controlled, crossover trial

Heat exposure's effect on glucose tolerance depends on the amount of body exposed, likely relating to autonomic nervous system balance. We assessed how partial-body heat exposure at two different levels of the lower extremities affects glucose tolerance and autonomic nervous system balance, measured via heart rate variability. We hypothesized feet-heating would improve glucose tolerance without affecting heart rate variability, while calf-heating would worsen glucose tolerance and decrease heart rate variability compared to a thermoneutral control condition. In a randomized, controlled, crossover trial, healthy participants' (N = 31, 23(3) years, 45% male) glucose tolerance was measured in (A) thermoneutral; (B) feet-heating; and (C) calf-heating conditions. Every 30 min for 2 h, blood glucose, heart rate, heart rate variability, tympanic temperature, thermal comfort scores, and blood pressure were measured. There were significant interactions between condition and time for blood glucose (F (4.6,72.6) = 2.6, p = 0.036), heart rate (F (3.4, 54.5) = 3.5, p = 0.017), heart rate variability (F (4.3,63.2) = 7.5, p < .0001), tympanic temperature (F (8, 268) = 2.4, p = 0.014), and thermal comfort scores (F (8, 248) = 22.1, p < 0.0001). Calf-heating increased 90 min glucose (+12 (95% confidence interval, CI: 3-21) mg/dL, p = 0.013) and decreased heart rate variability throughout (mean decrease: 13%-22%, p < 0.007), while feet-heating lowered 90 min glucose (-7 (95% CI: -16 to +1) mg/dL, p = 0.090) without affecting heart rate variability (p = 0.14-0.99). Blood pressure and body temperature were similar between conditions, but heart rate and thermal comfort scores increased with heating. Calf-heating worsens, while feet-heating may improve, glucose tolerance. Changes in heart rate variability coincided with changes in glucose tolerance despite unchanged body temperature. Whether heart rate variability can be used to monitor autonomic nervous system balance during heating to optimize its acute effect on glycemic indices should be further explored.

Efficacy of Ḥammām-i-yābis (dry bath) in metabolic syndrome: a single arm, open-labelled clinical trial

OBJECTIVES

This study intended to evaluate the efficacy of Ḥammām-i-yabis (dry bath) in metabolic syndrome as primary objective and perceived improvement and changes in quality of life as secondary objective.

METHODS

The study was designed as single arm, open-labelled, pre and post without control clinical trial comprising 30 diagnosed cases of metabolic syndrome belonging to 20-50 years of age of either sex. The enrolled patients were exposed to the dry heat of Ḥammām-i-yābis for 15 min at a temperature of 60 degree centigrade on every third day for a duration of 30 days (a total of 10 sittings). Objective parameters comprising systolic and diastolic blood pressure and waist circumference were assessed on every follow up, while other objective parameters (FBS, HDL and Serum Triglycerides) were assessed before and after the study.

RESULTS

Significant statistical difference was observed in objective parameters. Two tailed paired Student's t-test, (for pre and post) and repeated measure ANOVA (for 0, 15th and 30th day) were used to find the significance of mean change in study parameters. No significant adverse change appeared in safety parameters.

CONCLUSIONS

Ḥammām-i-yābis was found effective, safer, more feasible and less expensive regimenal modality for the patients of metabolic syndrome.

Effects of 12 sessions of steam bath intervention on spirometry parameters among healthy adult volunteers

OBJECTIVES

Steam bath is extensively used around the world. However, its physiological influence is not understood in detail. Objective of the current study is to examine the effects of 12 sessions of steam bath on spirometric parameters among healthy participants.

METHODS

Forty healthy adult volunteers of both sex (14 male and 26 female) aged 26.38 ± 8 years participated in the study. A steam bath session (10-15 min) was given once a week for 12 weeks. The spirometric parameters [forced expiratory volume in the 1st second (FEV1, L), forced vital capacity (FVC, L), FEV1/FVC ratio (absolute value), maximal mid-expiratory flow (MMEF, L/s) and peak expiratory flow (PEF, L/s)] were measured by Helios 401 spirometer.

RESULTS

Compared to baseline, post-intervention spirometric parameters showed significant (p<0.05) improvement in the FVC (82.40 ± 11.24 to 96.91 ± 18.76), FEV1 (86.13 ± 14.39 to 91.17 ± 12.48), FEV1/FVC ratio (86.96 ± 3.64 to 93.75 ± 4.80), MMEF 25-75% (86.96 ± 3.64 to 94.16 ± 11.57), peak expiratory flow rate (79.82 ± 14.90 to 92.18 ± 18.96).

CONCLUSIONS

Taking steam bath improves the spirometric parameters of healthy adult participants. However, future randomized controlled trials with on a large scale have to done to validate our findings.