Table 2.

Human studies on effects of physical activity on peptides and cognition: Ghrelin.

Reference	Subjects	Target Area	Type of PA	(Neuro) Peptide	Main Results
Controlled trial [38]	12 M Healthy Exercise status was not mentioned 19–29 years old No fasted state	Levels of plasma acylated ghrelin	Acute sprint interval and endurance exercise	Ghrelin	Sprint interval exercises lead to greater suppression in plasma acylated ghrelin levels.
Randomized crossover [39]	9 M Healthy Physically active 19–25 years old Fasted state	Levels of plasma acylated ghrelin	Acute aerobic exercises	Ghrelin	Single sessions of aerobic exercises lead to lower plasma levels of acylated ghrelin.
Randomized crossover [40]	11 M Healthy Physically active 19–23 years old Fasted state	Levels of plasma acylated ghrelin	Acute aerobic and resistance exercises	Ghrelin	Aerobic and resistance exercises lead to lower plasma levels of acylated ghrelin.
PA intervention, no control group [41]	5 M Healthy Sedentary 26 ± 1 years old Fasted state	Levels of plasma ghrelin	Acute incremental exercise until exhaustion	Ghrelin	Acute incremental exercise lads to decrease in plasma ghrelin levels.
Randomized crossover [42]	12 M overweight Sedentary 48 ± 5 years old Fasted state	Levels of plasma acylated ghrelin	Acute aerobic, strength and combined (aerobic and strength) exercises	Ghrelin	Single sessions of aerobic exercises lead to lower plasma levels of acylated ghrelin. Strength and combined exercises did not alter acylated ghrelin levels.
Randomized crossover [43]	18 M and F Healthy Physically active 19–32 years old Fasted state	Levels of total plasma ghrelin	Acute aerobic exercises	Ghrelin	Aerobic exercise did not alter total ghrelin levels.
Counter-balanced [44]	9 M Healthy Physically active 25 ± 1 years old Fasted state	Levels of plasma ghrelin	Acute resistance exercises	Ghrelin	Eccentric resistance exercises did not alter ghrelin levels and concentric resistance exercises suppressed ghrelin levels.
Randomized counter-balanced [45]	10 M Physically active 21 ± 1 years old Fasted state	Levels of plasma active ghrelin	Acute aerobic and resistance exercises	Ghrelin	Resistance exercises suppress plasma active ghrelin levels. Aerobic exercise did not alter plasma active ghrelin levels.
Longitudinal study [46]	22 M and F Overweight Sedentary 37 ± 8 years old Fasted state	Levels of plasma acylated ghrelin	Regular aerobic exercises	Ghrelin	Long-term aerobic training program results in slight increase in plasma acylated ghrelin levels.
RCT [47]	33 M overweight Sedentary 49 ± 7 years old Fasted and postprandial state	Levels of plasma active ghrelin	Regular aerobic and regular resistance exercises	Ghrelin	Aerobic and resistance exercises result in no change in acylated ghrelin levels in fasted and postprandial state.
Randomized trial [48]	20 M Healthy Sedentary 33 ± 2 years old Fasted state	Levels of plasma active ghrelin	Regular aerobic exercises in normoxic and normobaric hypoxic conditions	Ghrelin	4-week program of aerobic exercises in normoxic and normobaric hypoxic conditions result in no change in active ghrelin levels.

M, males; F, females; RCT, randomized controlled trial; PA, physical activity.