Observing the changes in any muscle while working in Force – Class 8 Science Experiment

Chapter Name: Force

Activity Name: Observing the changes in any muscle while working in Force

Activity Description:

The experiment aims to observe changes in muscles while performing different exercises using a dumbbell. By lifting the dumbbell in various ways, participants will observe which muscles are being shortened and which ones are relaxing. This activity highlights how muscles work in pairs, where one group contracts while the other group relaxes.

Required Items:

  1. Dumbbell (weight of your choice)

Step by Step Procedure:

  1. Gather all the required items, including the dumbbell.
  2. Assemble a group of participants, including yourself and your friends.
  3. Choose a suitable exercise area with enough space to perform the experiment safely.
  4. Each participant should take turns performing different exercises with the dumbbell, such as bicep curls, shoulder presses, and lateral raises.
  5. While performing the exercises, pay close attention to the muscles involved in each movement.
  6. Observe which muscles are shortening (contracting) during the lifting phase of the exercise.
  7. Also, observe which muscles are relaxing (expanding) during the lowering phase of the exercise.
  8. Take note of the specific muscles involved in each exercise and their corresponding actions (shortening or relaxing).

Experiment Observations:

  • During bicep curls, the muscles in the front of the upper arm (biceps) will shorten while the muscles in the back of the upper arm (triceps) will relax.
  • During shoulder presses, the muscles in the front and middle of the shoulder (deltoids) will shorten while the muscles in the back of the shoulder (posterior deltoids) will relax.
  • During lateral raises, the side shoulder muscles (lateral deltoids) will shorten while the back shoulder muscles (posterior deltoids) will relax.


  1. Use a dumbbell weight that is suitable for each participant’s strength and ability to avoid injuries.
  2. Ensure proper lifting techniques are followed to prevent strains or sprains.
  3. Warm up before starting the exercises to prepare the muscles for physical activity.
  4. If any participant experiences discomfort or pain during the experiment, they should stop immediately and seek medical advice if necessary.

Lesson Learnt from Experiment:

The experiment demonstrates how muscles work in pairs to facilitate movement. As one group of muscles contracts or shortens to perform a specific action, the opposing group of muscles relaxes or lengthens.

This coordinated action allows smooth and controlled movements, whether it’s lifting a dumbbell or performing everyday tasks. Understanding how muscles work together can help individuals tailor their workouts and improve their overall physical performance.

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