Study finds solar radiation influences exercise intensity - Preliminary research has found evidence that exposure to sunlight reduces self-regulated exercise intensity outdoors, suggesting use of a sunshade to reduce solar radiation might be of benefit to maintain endurance exercise performance.

See the source article by following the link below:
Study finds solar radiation influences exercise intensity - Preliminary research has found evidence that exposure to sunlight reduces self-regulated exercise intensity outdoors, suggesting use of a sunshade to reduce solar radiation might be of benefit to maintain endurance exercise performance.