Page 79 - JSOM Fall 2023

FIGURE 2 Changes in metabolic hormones following cold- FIGURE 3 Changes in growth-related hormones following cold-
water dives in military personnel. Concentrations of (A) Total water dives in military personnel. Concentrations of (A) Testosterone,
Triiodothyronine (T3), (B) Free Triiodothyronine (fT3), (C) Thyroxine (B) Insulin-like growth factor 1 (IGF-1), (C) Dehydroepiandrosterone
(T4), (D) Free Thyroxine (fT4), (E) Thyroid-Stimulating Hormone (DHEA), (D) Insulin-like growth factor-binding protein 3 (IGFBP-3),
(TSH), (F) Thyroid-Binding Globulin (TBG), and (G) Leptin were and (E) Sex hormone-binding globulin (SHBG) were measured (Pre)
measured before (Pre) and after the first (Post 1) and second (Post 2) and after the first (Post 1) and second (Post 2) dive of the day. Each
dive of the day. Each circle represents one participant’s value and the circle represents one participant’s value, and the bars represent the
bars represent the mean concentration for each time point (T3, fT3, mean concentration for each time point (n=5).
T4, fT4, TSH, and Leptin: n=5; TBG: n=3).

*p < 0.05 vs. Pre; # p < 0.05 vs. Post 1, †p < 0.05 vs. respective value
*p < 0.05 vs. Pre; #p < 0.05 vs. Post 1, †p < 0.05 vs. respective value on day 1.
on day 1.
0.3°C and was not different between time points or between
(p < 0.001; Figure 3B) and SHBG (p < 0.002; Figure 3E); and days (p > 0.05). Skin temperature was significantly decreased
an interaction effect (day vs. time) for SHBG (p < 0.001; Fig- (p < 0.001) post-dive across all dives as compared to Pre values
ure 3E). Pairwise comparisons revealed significantly lower but there were no differences between post-dive skin tempera-
testosterone concentrations following both dives across both ture between days or dives (pre-dive: 32.6 ± 0.6°C; post-day
days (p < 0.001; Figure 2A). On day 3, IGF-1 concentrations 1: 27.6 ± 1.2°C; post-day 2: 27.6 ± 1.3°C). USG averaged
were significantly decreased across both dives and between 1.028 ± 0.001 daily indicative of mild dehydration but was
days (p < 0.001; Figure 3B). No effects of time or day were unchanged between days (p > 0.05). There was no effect of
observed for IGFBP-3 (p > 0.05). In line with IGF-1 results, diving on grip strength either within or between days (average
plasma DHEA concentrations were significantly decreased pre: 125.7 ± 20.4-lb; post: 125.1 ± 12.9-lb, > 0.05). Average
across dives and between days (p < 0.001; Figure 3C). Plasma heart rate between dives was not different for day 1 (day 1,
SHBG concentrations significantly decreased across day 1 and dive 1: 114 ± 9 beats per minute (bpm); dive 2: 118 ± 6 bpm;
remained suppressed on day 3 (p < 0.001; Figure 3E). Interest- p > 0.05). However, there was a main effect of time for day 2
ingly, the evening of day 3 measured a significant increase as (day 2, dive 1: 116 ± 6 bpm; dive 2: 94 ± 9.2 bpm; p = 0.03).
compared to Pre values (p < 0.001; Figure 3E).
Discussion
Metabolic Parameters
A within-by-within analysis of metabolic parameters uncov- Twice-daily active cold-water diving increased SAM/SNS ac-
ered a main effect of time (Pre vs. Post) for glucose and FFA, a tivity while attenuating HPA response and hormones related to
main effect of day (day 1 vs. day 3) for FFA and an interaction recovery (e.g., testosterone, DHEA) and metabolism (leptin).
effect (day vs. time) for FFA, ketones, and glucose (p < 0.05; IGF-1 showed a delayed suppression over time (between day
Figure 4). However, all values were within normal physiologi- differences). Moreover, un-Ocn decreased with diving but re-
cal range. Respiratory exchange ratio (RER) values measured covered between days. Collectively, our data suggest that re-
immediately after each dive were above 0.95 (0.95–1.06) and peated cold-water diving alters the acute stress response and
were not different between time points (p > 0.05). potentially impacts markers of metabolism, muscle recovery,
and bone turnover. While these data collected are in a small
Physiological Data. Body weights were not affected by the cohort, the lack of recovery in several hormones over only a
training dives or different between days and averaged 83.5 few days suggests that repeat submersion in cold water may
± 4.7kg (p > 0.05). Core temperature (Tc) averaged 37.5 ± alter the physiological response to cold.

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