Lose weight (mass) or train? - effect of losing weight (mass) on power

In summary, the conversation discusses the potential effects of losing body mass on a rider's power output, with the example of a 75 kg rider producing 250 W of power. It is suggested that a decrease in mass can potentially lead to an increase in power, particularly in situations where changes in height or acceleration are involved. However, it is also noted that the decision between losing weight or training harder ultimately depends on the individual's specific circumstances and goals.
  • #1
Byrne
20
0
Lose weight (mass) or train? -- effect of losing weight (mass) on power

I'm having troubles wrapping my head around this one (I've provided the example from my class notes below):

Q: Is it better to lose 5 kg of body mass (assume no change in muscle strength) or to train harder and gain 15 W of power?

Given:
75 kg rider producing 250 W of power

ANSWER:

75 kg / 70 kg = 1.071
In terms of Watts: 250 W x 1.071 = 268 W, ~ 18 W increase

So, depending on the initial weight, the athlete might see as large a benefit from losing weight as training harder.

My question -- how does a decrease in the mass of the rider increase his power producing ability by 18 W? Intuitively, I would think that a rider with lower mass will experience less resistive forces when riding (i.e., gravity when on an incline, kinetic friction) and so can sustain the same velocity as a heavier rider without applying as much force and, therefore, less power.

From a physics standpoint, how does a mass decrease result in an increase in Power as this example suggests (taken from my class notes)?

Thanks!
 
Physics news on Phys.org
  • #2


If it was strictly moving at constant velocity and his air resistance profile doesn't change, it might not.

But when you take into account changes of height - like a hill - where effort is going into increasing gravitational potential, then he would benefit from the lower mass, as that would be less work. Or any starts and stops where he would be accelerating.

The lecturer was merely trying to get you to think about the consequences of getting heavier. The harder training and weight gain would need to develop an additional amount of power to be worth it I think is the point.
 
  • #3


I would approach this question by looking at the scientific principles involved in weight loss and power production.

Firstly, it is important to understand that weight loss does not necessarily mean a decrease in muscle mass. With proper nutrition and training, it is possible to lose fat mass while maintaining or even increasing muscle mass. Therefore, the assumption of no change in muscle strength in this scenario is not entirely accurate.

Next, let's consider the relationship between power and weight. Power is defined as the rate at which work is done, and work is the product of force and distance. When it comes to cycling, the force applied is the force pushing against the pedals, and the distance is the distance the pedals travel. This means that for a given power output, a lighter rider will have to apply less force to the pedals compared to a heavier rider. This is because the lighter rider has less mass to move and therefore requires less force to travel the same distance.

Now, let's consider the effect of losing weight on power production. As mentioned earlier, weight loss does not necessarily mean a decrease in muscle mass. However, even if there is a slight decrease in muscle mass, the decrease in weight will still result in a decrease in the force required to produce the same power output. This means that the rider can now produce the same power with less effort, allowing them to potentially increase their power output.

Additionally, weight loss can also improve the efficiency of the rider's body. This is because less energy is required to move a lighter body, meaning more energy can be directed towards power production. This is similar to how a car with less weight can accelerate faster and reach higher speeds.

In conclusion, while both losing weight and training can result in an increase in power, weight loss can have a significant impact due to the reduced force required to produce the same power output. However, it is important to note that weight loss should be done in a healthy and sustainable manner to ensure it does not negatively affect muscle mass and overall athletic performance.
 

Related to Lose weight (mass) or train? - effect of losing weight (mass) on power

What is the effect of losing weight on power?

Losing weight can have a significant effect on power, as it reduces the load on the body and allows for more efficient movement. However, the amount of power gained or lost will depend on the individual's body composition, training regimen, and overall health.

How much weight loss is needed to see an increase in power?

The amount of weight loss needed to see an increase in power will vary for each individual. Generally, a 5-10% decrease in body weight can lead to improvements in power. However, it's important to maintain a healthy weight and not lose too much mass, as this can have negative effects on overall performance and health.

Can losing weight negatively affect power?

Yes, losing too much weight or losing weight too quickly can have negative effects on power. This is because weight loss can also mean a loss of muscle mass, which is essential for power production. It's important to lose weight in a healthy and gradual manner to maintain muscle mass and overall strength.

Is it better to lose weight or train for improving power?

Both losing weight and training can have positive effects on power, but the best approach will depend on the individual's goals and body composition. For someone with excess body fat, losing weight may be more beneficial for improving power, while someone with a lower body fat percentage may benefit more from focused training to increase muscle mass and power.

How can I maintain power while losing weight?

To maintain power while losing weight, it's important to focus on maintaining muscle mass through strength training and consuming enough protein. It's also crucial to lose weight gradually and in a healthy manner, rather than drastically cutting calories or engaging in extreme diets. Adequate rest and recovery are also essential for maintaining power during weight loss.

Similar threads

  • Introductory Physics Homework Help
Replies
13
Views
2K
  • Introductory Physics Homework Help
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
2K
  • Introductory Physics Homework Help
Replies
8
Views
7K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
4
Views
897
Replies
2
Views
2K
Replies
3
Views
198
  • Introductory Physics Homework Help
Replies
20
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
5K
Back
Top