Does being overweight affect swimming performances?

Pam, I think you might be thinking too much about 20 lbs of weight. In and of itself it's a relatively minor factor in how fast you swim. Your weight (resulting from gravity pulling your mass towards the center of the earth) is a downward force. However, water exerts an upward buoyant force (equal to the weight of the displaced fluid as you lie in the water) and that upwards force counterbalances all or a great deal of your weight, which is generally why you float. (Floating is somewhat more complicated involving your density (weight per unit volume) and the density of the water you are in.) To move forward in the water you must exert enough propulsive force through your pull and kick to overcome the fluid's resistance to movement - that resistance is called drag. Drag depends on 4 properties (none are directly weight): the fluid (density), the size (form or cross-sectional area in the water) of the swimmer, Coefficient of Drag (depends on shape) of the swimmer, and on the square of the speed of the swimmer. The fluid density, cross sectional area, and coefficient of drag are very similar from one swimmer to the next, although they can vary somewhat or be tinkered with. Thus the biggest factor influencing how much propulsion you need to exert to overcome drag and move through the water is velocity. If you want to swim twice as fast, you have to increase propulsive force by a factor of 4, because drag increases with the square of the velocity. Similarly, the amount of power or energy you spend increases with cube of the velocity. To achieve such a substantial increase in velocity and propulsive force, you have to get stronger and/or pull and kick more efficiently. These are far more important than weight. Getting stronger and retaining muscle mass gets harder as you age, but it can still be done. Improving your stroke and kick (technique) to become more efficient is a great way to get faster and swimming with a masters program and coach should really help. Focus on strength (to the extent you can) and technique and don't worry about weight too much. Its great that you are swimming- a non-weight bearing sport and your engine is water cooled! Keep going.

Pam, I think you might be thinking too much about 20 lbs of weight. In and of itself it's a relatively minor factor in how fast you swim. Your weight (resulting from gravity pulling your mass towards the center of the earth) is a downward force. However, water exerts an upward buoyant force (equal to the weight of the displaced fluid as you lie in the water) and that upwards force counterbalances all or a great deal of your weight, which is generally why you float. (Floating is somewhat more complicated involving your density (weight per unit volume) and the density of the water you are in.) To move forward in the water you must exert enough propulsive force through your pull and kick to overcome the fluid's resistance to movement - that resistance is called drag. Drag depends on 4 properties (none are directly weight): the fluid (density), the size (form or cross-sectional area in the water) of the swimmer, Coefficient of Drag (depends on shape) of the swimmer, and on the square of the speed of the swimmer. The fluid density, cross sectional area, and coefficient of drag are very similar from one swimmer to the next, although they can vary somewhat or be tinkered with. Thus the biggest factor influencing how much propulsion you need to exert to overcome drag and move through the water is velocity. If you want to swim twice as fast, you have to increase propulsive force by a factor of 4, because drag increases with the square of the velocity. Similarly, the amount of power or energy you spend increases with cube of the velocity. To achieve such a substantial increase in velocity and propulsive force, you have to get stronger and/or pull and kick more efficiently. These are far more important than weight. Getting stronger and retaining muscle mass gets harder as you age, but it can still be done. Improving your stroke and kick (technique) to become more efficient is a great way to get faster and swimming with a masters program and coach should really help. Focus on strength (to the extent you can) and technique and don't worry about weight too much. Its great that you are swimming- a non-weight bearing sport and your engine is water cooled! Keep going.