2) Could muscle fiber type have had an influence on your results with muscle fatigue?
Answer: Red muscle has myoglobin which stores oxygen and makes it available for gusto production during contraction of muscle. Hence they are less prone to fatigue. White muscle doesnt have much myoglobin and will fatigue faster. Marathon runners enjoy more proportion of red muscle fibres in their muscles and are competent to sustain their activity for a longer period. Sprinters enjoy more of white muscle fibres and are better suited for short bursts of intense activity.