Involuntary, voluntary and skeletal muscle
There are three types of muscle in the body:
- smooth muscle – found in the internal organs and blood vessels - this is involuntary
- cardiac muscle – found only in the heart - this is involuntary
- skeletal muscle – attached to the skeleton - this is voluntary
Involuntary muscles are not under our conscious control which means we can't make them contract when we think about it.
Voluntary muscles are under our conscious control so we can move these muscles when we want to. These are the muscles we use to make all the movements needed in physical activity and sport.
The main skeletal muscles of the human body are shown here.
| Function | Example in sport | |
| Deltoid | Lifting the arm at the shoulder (the deltoid muscle has different parts which flex, extend and abduct the shoulder joint) | Lifting the arms to block in volleyball; upward arm swing when trampolining |
| Trapezius | Shoulder horizontal extension (moving the arms backwards at shoulder level) | Preparation phase of an overarm throw or badminton smash |
| Pectorals | Adduction of the shoulder (moving the arm towards the body); Shoulder horizontal flexion (moving the arms forwards in front of the body) | Upwards phase of a press up; rugby player making a tackle |
| Triceps | Extension of the elbow (straightening the arm) | Shooting and chest passing in netball (execution phase) |
| Biceps | Flexion of the elbow (bending the arm) | Drawing a bow in archery; 'backscratch' position during tennis serve |
| Abdominals | Flexion of the spine (sitting upwards) | Performing a sit up or a forward roll |
| Latissimus dorsi | Adduction of the shoulder (moving the arm down towards the mid-line of the body) | Hitting in hockey – left shoulder during preparation, right shoulder during execution and recovery |
| Gluteals | Hip extension (moving the femur backwards) | Pulling leg back at the hip before kicking a ball |
| Quadriceps | Extension of the knee (straightening the leg) | Kicking a ball (execution and recovery phase) |
| Hamstrings | Flexion of the knee (bending the leg) | Performing a hamstring curl on a weights machine; preparation phase of a rebound jump in basketball |
| Gastrocnemius | Plantar flexion of the ankle (pointing the toes downwards) | Standing on tiptoe to mark a shot in netball or pointing the toes during a gymnastic or dance move |
| Deltoid | |
|---|---|
| Function | Lifting the arm at the shoulder (the deltoid muscle has different parts which flex, extend and abduct the shoulder joint) |
| Example in sport | Lifting the arms to block in volleyball; upward arm swing when trampolining |
| Trapezius | |
|---|---|
| Function | Shoulder horizontal extension (moving the arms backwards at shoulder level) |
| Example in sport | Preparation phase of an overarm throw or badminton smash |
| Pectorals | |
|---|---|
| Function | Adduction of the shoulder (moving the arm towards the body); Shoulder horizontal flexion (moving the arms forwards in front of the body) |
| Example in sport | Upwards phase of a press up; rugby player making a tackle |
| Triceps | |
|---|---|
| Function | Extension of the elbow (straightening the arm) |
| Example in sport | Shooting and chest passing in netball (execution phase) |
| Biceps | |
|---|---|
| Function | Flexion of the elbow (bending the arm) |
| Example in sport | Drawing a bow in archery; 'backscratch' position during tennis serve |
| Abdominals | |
|---|---|
| Function | Flexion of the spine (sitting upwards) |
| Example in sport | Performing a sit up or a forward roll |
| Latissimus dorsi | |
|---|---|
| Function | Adduction of the shoulder (moving the arm down towards the mid-line of the body) |
| Example in sport | Hitting in hockey – left shoulder during preparation, right shoulder during execution and recovery |
| Gluteals | |
|---|---|
| Function | Hip extension (moving the femur backwards) |
| Example in sport | Pulling leg back at the hip before kicking a ball |
| Quadriceps | |
|---|---|
| Function | Extension of the knee (straightening the leg) |
| Example in sport | Kicking a ball (execution and recovery phase) |
| Hamstrings | |
|---|---|
| Function | Flexion of the knee (bending the leg) |
| Example in sport | Performing a hamstring curl on a weights machine; preparation phase of a rebound jump in basketball |
| Gastrocnemius | |
|---|---|
| Function | Plantar flexion of the ankle (pointing the toes downwards) |
| Example in sport | Standing on tiptoe to mark a shot in netball or pointing the toes during a gymnastic or dance move |