They should be avoided. In heavy, unshaved training, they could assist some swimmers to improve in performance. Once a taper is experienced, and a swimmer is shaved, they would serve no other advantage other than to increase a swimmer's flotation. One should not believe the advertising claims for these suits. For example, in Adidas advertisements, Alex Popov is shown wearing Adidas bodysuits but in Olympic races, and when he set the 50-m world record at the Russian trials, he wore a traditional brief suit.
Some fabric stretching occurs with each wearing.
Swimmers are advised to wear the suits a few times at practice, to produce some accommodating stretch, before using them in races. When suits feel uncomfortable, it might be necessary to cut extra pieces out of the suit. This occurs often on the upper back so that outward rotation of the scapulae is not hindered. For swimmers with heavy thighs, the above-knee seams can be too restrictive and might need to be cut to free up circulation and the function of muscle tendons. Age-groupers can gain much more by swimming with good technique and training with sensible volume.