Question

Why are slow-twitch muscles more beneficial than fast-twitch muscles for cardiorespiratory fitness?

Answer 1

Answer is d) 
Slow twitch muscles are more important for cardiorespiratory fitness because they efficiently use oxygen.

fast twitch fibres are used in quick, high speed events such as sprints, in these situations there is not enough time for oxygen-rich blood to get to the muscles so fast twitch fibres do not use oxygen.

Slow twitch on the other hand, are used in endurance events like marathons when there is time for oxygen- rich blood to reach the muscles. This means that slow twitch fibres are better at using oxygen.

The efficient use of oxygen is important to cardiorespiratory fitness as it is concerned with the efficiency of the heart and lungs in transporting oxygen rich blood to muscles.

Answer 2

D Slow-Twitch Type I

Activities Marathons, distance running, swimming, cycling, power walking, endurance training. Muscle Fiber Size Small. Force Production Low .Resistance to Fatigue Slow.Contraction Speed Slow. Mitochondria High. Capillaries High. Myoglobin High.ATPase Level Low. Oxidative Capacity High

Slow-twitch muscle fibers support long distance endurance activities like marathon running, while fast-twitch muscle fibers support quick, powerful movements such as sprinting or weightlifting. Slow-twitch muscle fibers have high concentrations of mitochondria and myoglobin. Although they are smaller than the fast-twitch fibers, they are surrounded by more capillaries. This combination supports aerobic metabolism and fatigue resistance, particularly important for prolonged submaximal (aerobic) exercise activities. Type I fibers produce less force and are slower to produce maximal tension (lower myosin ATPase activity) compared to type II fibers. But they are able to maintain longer-term contractions, key for stabilization and postural control.Slow-twitch muscle fibers are fatigue resistant, and focused on sustained, smaller movements and postural control. They contain more mitochondria and myoglobin, and are aerobic in nature compared to fast-twitch fibers. Slow-twitch fibers are also sometimes called type I or red fibers because of their blood supply. Fast-twitch muscle fibersprovide bigger and more powerful forces, but for shorter durations and fatigue quickly. They are more anaerobic with less blood supply, hence they are sometimes referred to as white fibers or type II.