Swimming

Introduction

Humans pay a price for the terrestrial specialization of their locomotion: of the forms of aquatic locomotion available including water jetting, hydrofoils for lift-based swimming, and oar-like paddling, only the last propulsion method is viable. While not as penalized as in horses with their thin appendages, human swimming is severely limited by the localization of most of the engine (71% of total muscle mass) in the non-propelling lower limbs (Nindl et al., 2002), and by a reduced surface of the available 'oars' (i.e. upper limbs, responsible of 88% of total thrust (Hollander et al., 1988)). The paddling surface (A, m2) is important because: (a) it contributes to the drag (=1/2·?·A·v2·CD, where ? is water density, v (m/s) is the oar speed and CD is the drag coefficient, which mainly depends on the 3D shape of the object), and (b) the propelling (Froude) efficiency increases if the same thrust is obtained by accelerating a larger amount of water to a lower speed (Alexander, 2003).'

Also, similar to the advantage brought by fins to the lower limbs (Zamparo et al., 2005), an increase in A and/or in CD could increase: (a) muscle efficiency, since contraction can occur at a slower speed, and (b) hydraulic efficiency, related to the energy required to move the propulsive machinery, because of the reduced mechanical internal work associated with a lower stroke frequency for the same thrust (Minetti, 2004).In competitive swimming, no passive tool is allowed to enhance performance; however, athletes are very frequently observed (and trained) to spread their fingers during a stroke.

Discussion

Swimming is a competitive sport in which humans move themselves through water. It is a popular recreational activity, in particular where the climate is hot and in areas with natural watercourses. Swimming carries many health benefits.

Low impact

When you exercise on land, such as running or walking, you put a lot of pressure on your joints, bones and muscles. With swimming, the buoyancy of water acts cushions your body and is no harsh pounding to stress your joints and muscles. In fact, swimming is regarded as one of the safest exercises, with very little risk of injury. And many people who have been injured turn to swimming as a way to exercise, and even rehabilitate their injuries. 

Anyone can do it

No matter your age, weight, skill level, or fitness level, swimming is an excellent choice for anyone including overweight people, people with disabilities , pregnant women and ...