GDF15 and chronic obstructive pulmonary disease: COPD patients show a fibre shift from a predominance of type I fibres to a predominance of type IIA fibres in the quadriceps muscle, and this change in fibre proportion is associated with a marked reduction in exercise capacity.38 However, GDF‐15 expression was not associated with fibre type within the muscle nor was there an association of serum GDF‐15 with fibre proportion.