Table 8.

Cold shock response studies.

Reference	Study Sample	Habituation Length	Habituation Temperature	Cold Testing Procedure	Results/Findings
Tipton [98]	11 M, 4 F; 8 in habituation group, 7 CON	6, 3 min head-out immersions in stirred cold water of the left side of the body over 3 days (2x/day)	10°C water; wearing swimming costume and halved wetsuit for non-immersed side	Pre and post testing: 3 min head-out immersions in stirred water at 10°C of the right side of the body	Repeated (6) left-side immersions ↓ the magnitude of HR, respiratory rate and volume responses during the 2nd right-side immersion in the habituation group without any change in Tsk
Tipton [100]	12 M; 8 in habituation group, 4 CON	6, 3 min head-out immersions over 3 days (2x/day)	15°C water; wearing swimming trunks	Pre and post (immediately following the completion of the 6 repeated immersions and again at 2, 4, 7, and 14 months) testing; 3 min head-out seated immersions in stirred water at 10°C wearing swim trunks	Habituated subjects: ↓ respiratory frequency, inspiratory minute volume, and HR during the 1st 30 sec of immersion immediately post repeated immersion (retained for 7 months); After 14 months, HR remained ↓ but respiratory frequency and inspiratory minute volume returned to near pre-habituation levels; Periodic immersions incurred by the CON group (as well as the greater volume of immersion in the habituation group) ↓ the duration of reactive elevation in HR, tidal volume, and inspired minute ventilation
Eglin [106]	13 M, 5 F	6 cold showers over 3 days (2x/day); 3 exposure groups: (1) 3 min at 10°C on the back (10B), (2) 3 min at 15°C on the back (15B), (3) 30 sec at 10°C on the back + 30 sec on the front (10BF)	10°C 15°C 10°C	Pre and post testing: 3 min head-out immersions in stirred water at 10°C wearing swim wear	Over first 30 sec of immersion, immersion respiratory frequency was ↓ by 21% in groups 10B and 10BF after repeated showers, but not 15B; the rate of change of skin temperature is an important factor in determining the degree of respiratory drive habituation
Barwood [101]	20 M; 10 M habituation, 10 M habituation + psychological skills training	5, 2.5 min head-out cold water immersions (2x/day) breathing freely	~12°C; wearing swimming trunks	Pre and post testing: 2.5 min seated, head-out immersions in stirred cold water (~12°C) wearing swimming trunks while maximally breath holding	Following repeated immersions, both habituation and habituation + psychological skills training ↑ breath holding time (by 73% and 120%, respectively), ↓ HR at 2 min of cold water immersion, and ↓ breathing frequency throughout cold water immersion
Barwood [110]	8 M, 4 F	7, 7 min head-out immersions (1x daily for 7 days); Immersions 1 and 7 were cold water (CWI) and immersions 2–6 were thermoneutral water (TWI)	CWI: 15°C TWI: 35°C Wearing a swimming costume	Longitudinal passive (time-focused) observation; Cold water immersions 1 and 7 served as a pre and post test	↓ in self-reported acute anxiety from CWI 1 to CWI 7 but ↔ in HR, breathing frequency, or minute ventilation as part of the cold shock response; Tidal volume ↓ from CWI 1 to CWI 7
Eglin [104]	9 M	5, 3 min head-out immersions into cold water over the course of a collective 55–120 min; rewarmed in 38°C for 3 minutes + 10 minute break between cold water immersions	15°C water; wearing swimming trunks	Pre and post testing: 2 head-out immersions into 15°C stirred cold water for 5 minutes wearing swimming trunks (IMM1 and IMM7); one week apart	HR ↓ throughout IMM7 compared to IMM1; inspiratory minute volume ↓ IMM7 compared to IMM1 over the 1st minute of immersion; respiratory frequency ↓ in the first 30 sec in IMM7 vs. IMM1; ↔ in inspiratory gasp and tidal volume
Barwood [105]	Group (1): 12 M, 4 F Group (2): 6 M, 4 F	7, 7 min head-out cold water immersions (1x daily for 7 days); Two experimental groups: (1) Repeated anxiety, where anxiety was raised for each immersion using deception and math tasks and (2) Acute anxiety, where deception was only used once for the 1st immersion	15°C water; wearing swimming costume	Longitudinal passive (time-focused) observation; Cold water immersions 1 and 7 served as a pre and post test	↔ in anxiety levels between immersions 1 (pre-control), 7 (post-control), and mean of habituation immersions for repeated anxiety group; Repeated anxiety during habituation resulted in failure of a habituation of the cold shock response even when additional anxiety was removed (↔ HR, respiratory frequency, tidal volume, or minute ventilation)