Athletes who play sports like basketball and tennis should avoid weight training because it slows them down and makes them inflexible

This is also absolute nonsense!! Athletes will not lose speed and flexibility from weight training. Only when athletes do not incorporate a stretching routine will they lose flexibility. Nobody has ever been unable to play a sport because of their muscle mass. On the contrary, stronger muscles enhance your sport performance.

Scientific studies proved that the bodies of weight trainers who did not even stretch were more flexible than untrained bodies.