Table 1

Mechanism

Ref	Author/journal	Year	Study type	Patients	Outcome	LOE
16	Morikawa et al Med Sci Sports Exerc	2001	Controlled trial	26 female runners, 23 age-matched controls	Exercise-trained females have a high level of orthostatic intolerance during LBNP. Increase in leg compliance may play an important role	2
17	Levine et al Circulation	1991	Controlled trial	7 athletes and 6 controls	Endurance athletes have greater diastolic chamber compliance and distensibility than non-athletes	2
18	Levine et al J Appl Physiol	1991	Controlled trial	8 high fit, 8 mid fit and 8 low-fit athletes	Calf compliance and carotid baroreflex response contributed to individualised response to LBNP	2
19	Esch et al Am J Physiol Heart Circ Physiol	2007	Controlled trial	8 athletes and 8 controls	Endurance athletes had larger increases in left ventricular end-diastolic volume compared with non-athletes despite similar right ventricular cavity area	2
20	Esch et al J Appl Physiol	2010	Controlled trial	8 athletes and 8 controls	Endurance athletes demonstrated a decreased left ventricular untwisting rate compared with non-athletes	2
21	Convertino Med Sci Sports Exerc	2003	Controlled trial	8 men	Expansion of vascular volume after exercise is associated with reduced heart rate response to baroreceptor stimulation	2
22	Ogoh et al J Appl Physiol	2006	Clinical trial	8 men	Cardiopulmonary baroreflex may be reset during exercise to a new operating point associated with exercise-induced change in cardiac filling volume	2
23	Ogoh et al J Physiol	2003	Clinical trial	14 men	Highly fit individuals depend more on maintenance of venous return to maintain upright body position	2
24	Convertino Med Sci Sports Exerc	1993	Critical review	NA	Increased stroke volume is the main mechanism of compensation in aerobic trained individuals	3

LBNP, lower body negative pressure; LOE, level of evidence.