Constraint-led changes in internal variability in running

We investigated the effect of a one-time application of elastic constraints on movement-inherent variability during treadmill running. eleven males ran two 35-min intervals while surface emg was measured. in one of two 35-min intervals,after 10 min of running without tubes,elastic tubes (between hip and heels) were attached,followed by another 5 min of running without tubes. to assess variability,stride-to-stride iemg variability was calculated. significant increases in variability (36% to 74%) were observed during tube running,whereas running without tubes after the tube running block showed no significant differences. results show that elastic tubes affect variability on a muscular level despite the constant environmental conditions and underline the nervous system's adaptability to cope with somehow unpredictable constraints since stride duration was unaltered. © journal of sports science and medicine.