Comparison Of Hsp70, Cognition, And Pain Following Passive Heating Or Walking In Older Adults: A Preliminary Analysis

Heat shock proteins (HSP) are major components of the cellular chaperone network responsible for regulating protein amyloid aggregation and may be neuroprotective against the deleterious effects of aging. PURPOSE: To observe the level of HSP expression, cognitive performance, and self-perceived pain following one hour of aerobic exercise or whole-body passive heating in older adults. METHODS: Twenty older adults (age: 68.5 + 4.2 years, BMI: 26.9 + 4.3 kg/m2, 11 female) participated in a randomized controlled trial, repeated for time. Participants completed one hour of either moderate intensity walking on a treadmill (TM; 65-75% of age-predicted maximum heart rate), seated passive heating (HEAT) in a controlled environmental heat chamber (35-40 °C, < 40% humidity), or seated control (CON) in a neutral climate (21-24 °C). Participants were randomly assigned to an intervention (CON: n = 6, HEAT: n = 7, TM: n = 7). HSP70 was measured via blood samples with an enzyme-linked immunosorbent assay (ELISA) kit for HSP70. Blood samples were collected immediately and 24 hours following each intervention. Cognitive performance was measured after each intervention using computerized software. Pain was assessed via the McGill Pain Questionnaire after each intervention. RESULTS: Detectable amounts of HSP70 were analyzed for 6 participants. There were no statistical differences for HSP70 concentration between groups immediately or 24 hours following each intervention (p > 0.05). Reaction time was faster in HEAT versus CON (p = 0.006), but did not change for time (pre vs. post- HEAT: 1827.6 ± 194.9 vs 1583.0 ± 397.2 ms; CON: 2331.0 ± 853.1 vs 2077.3 ± 643.1 ms; TM: 1904.4 ± 214.5 vs 1682.3 ± 385.1 ms). Measures of cognitive flexibility were higher for HEAT (26.6 ± 6.9) compared to CON (19.9 ± 6.6, p = 0.029), but not TM (23.6 ± 5.0, p = 0.425). Response inhibition was greater for HEAT compared to CON (25.2 ± 9.9 vs 35.2 ± 8.6, p = 0.012), but TM did not differ between groups. Pain was perceived greater for TM and HEAT compared to CON (TM: 28 ± 21, p = 0.003; HEAT: 29 ± 10, p = 0.004; CON: 10 ± 12). CONCLUSION: One bout of aerobic exercise or passive heating may not illicit changes in HSP70 or impair cognition in older adults. There may be an anticipatory psychological affect resulting in different perceptions of pain for passive heating and exercise.