Exogenous Cortisol Administration; Effects on Risk Taking Behavior, Exercise Performance, and Physiological and Neurophysiological Responses

Figures

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  Figure 1. Schematic representation of the intervention trials with resting and exercise measures at their relevant time points. Physiological measures at rest; EEG and NIRS, salivary cortisol (Sa), blood glucose (gluc), and blood lactate (La). Balloon Analog Risk Task (BART) completed following all resting measures. Measures during exercise at steady state (SS) time points; NIRs, EEG. Measures during each sprint (S); NIRs. Blood samples (glucose and lactate) taken at two time points throughout, BL1 and BL2. Salivary cortisol (Sa) taken at 10 min post-exercise.

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  Figure 2. Salivary cortisol responses at rest and 10 min post-exercise. Values were significantly higher in COR (•) than PLA (o) at the same time point, at 45 (*P < 0.05), 60 and post-exercise (**P < 0.01). Salivary cortisol levels significantly increased across the COR trial, being higher at 45, 60, and post-exercise compared to 0 (aP < 0.05), 15 (bP < 0.05), and 30 (cP < 0.01). PLA increased significantly at post-exercise (#P < 0.01) compared to all other time points in the PLA condition. Post-exercise PLA values were also higher than COR at 0 and 15 min (δP < 0.01). PLA decreased from 0 to 30 min (+P < 0.01).

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  Figure 3. EEG Alpha slow (αs) bandwidth responses to COR (•) and PLA (o) in ANTPFC (A), VLPFC (B), and MC (C) during rest presented as % change from rest (0 min) to 15, 30, 45, and 60 min post-ingestion. (A): The COR trial was significantly higher in the ANTPFC (*P < 0.05) compared to PLA. (B): αS increased across time with 60 min being significantly higher than both 15 and 30 min (*P < 0.05). (C): In the MC αS increased in the COR trial from 30 to 45 min (*P < 0.05).

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  Figure 4. EEG Gamma bandwidth responses to COR (•) and PLA (o) in ANTPFC (A), VLPFC (B), and MC (C) during rest. Presented as % change from rest (0 min) to 15, 30, 45, and 60 min post-ingestion. There was a trend for percentage change at COR 60 (3.88 ± 5.1%) to be higher than COR 15 (0.14 ± 6.2%) (#P = 0.07).

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  Figure 5. BART test number of pumps (A) and number of adjusted pumps (B) in cortisol (COR), placebo (PLA), and baseline (BASE). The COR trial was significantly higher than BASE in the total number of pumps made (A) (**P < 0.01) and the number of pumps made adjusted for the number of bursts (B) (*P < 0.05).

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  Figure 6. Average power output (PO) during the COR (•) and PLA (o) trials during the steady state (SS) periods (A) and the sprints (B). During steady state PO decreased from SS2 to SS4 and SS5 (*P < 0.05).

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  Figure 7. Tissue oxygenation responses (TOI) in COR (•) and PLA (o) as % change from rest (60 min) to each steady state (SS) (A) and Sprint (Spr) (B) interval. Main effect of drug (a) and time (b). Significant differences in COR from 60 to Spr 1 (**P < 0.01). Trend for COR Spr 4 and 5 (#P = 0.06 and 0.07 respectfully) to be lower than COR 60. COR significantly lower than PLA 60 at Spr 1, 4, and 5 (&P < 0.05). Significant difference between COR and PLA at Spr 5 (δP < 0.05).

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  Figure 8. Normalized tissue hemoglobin (nTHI) in COR (•) and PLA (o) as % change from rest (60 min) to each steady state (SS) (A) and Sprint (Spr) (B) interval. Trend for COR Spr 4 and 5 (#P = 0.09 and 0.07 respectfully) to be lower than PLA.