Table 1.

Barriers to start with exercise or to remain engaged in exercise, as these have been described for persons with PD. References are grouped according to the type of study (randomized clinical trial – RCT, cohort study, qualitative study or review)

	RCTs	Cohort studies	Qualitative studies	Reviews
Factors related to body structure and function
General health barriers (not related to PD)		[17–20]	[10, 15]
Physical discomfort with exercise		[17]
PD motor symptoms		[20]	[25]	[16]
PD non-motor symptoms
Fluctuations in motivation	[12]			[24]
Anxiety			[23, 25]	[24]
Depression		[17, 18, 21, 22]	[23]	[16, 24]
Fatigue		[21]	[15, 25]	[16]
Apathy			[15]	[16]
Factors related to activities and participation
Low previous physical activity level or sport participation		[21]
Personal factors
Low self-efficacy		[19, 22]	[23]	[11, 16, 24, 26]
Reduced balance self-efficacy or fear of falling		[17, 18, 20]		[24]
Low outcome expectations from exercise		[17]		[11, 16]
Lack of time		[17]	[10]	[16]
Environmental factors
Lack of social support		[21]
Lack of an exercise partner		[20, 21]
Discomfort of seeing advancing symptoms of peers when exercising in a group			[23]	[16, 24]
Poor accessibility of the exercise location and lack of transportation to this location		[21]	[10]	[16]
Bad weather		[17, 20]	[25]
Cultural challenges				[16]
Financial burden of exercise				[16]
Wariness of moving in a crowded environment			[25]