title: Determining if muscle activity is related to preferred stride frequency during running in the water and on land.
abstract: OBJECTIVE
  To determine if muscle activity is related to preferred stride frequency (PSF) during deep water running (DWR) and treadmill running on dry land (TMR).
  
  
  METHODS
  Subjects (n = 11; 26.2 ± 4.4 years) completed TMR and DWR at their mode-specific preferred stride frequency (PSF mode). They also ran at stride frequencies which were lower and higher than the PSF mode (i.e., PSF mode ± 5, 10, and 15 %). Muscle activity from the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GL), SF, and rating of perceived exertion (RPE) were measured.
  
  
  RESULTS
  The PSF mode during DWR was significantly lower than that of TMR (i.e., 49.9 ± 11.0 versus 81.9 ± 4.8 strides/min, P < 0.0001). Additionally, muscle activity from the RF, TA, and GL during DWR was significantly lower than during TMR at respective PSF mode (~83.6 % decrease, P < 0.0001). However, RPE while running at the PSF mode during DWR and TMR was similar. During DWR, the RF, TA, and GL muscle activity was not different between PSF mode and any other SF conditions (P > 0.0005). During TMR, there was no significant difference in the RF and GL muscle activity between PSF mode and any other SF conditions during TMR (P > 0.0005).
  
  
  CONCLUSIONS
  During DWR, subjects selected a lower PSF than during TMR even though RPE was the same. It was also determined that the relationship between muscle activity and changes in SF relative to the PSF mode was unique during DWR and TMR.
authors.affiliation: Graduate School of Human-Environment Studies, Kyushu University, 6-1 Kasuga-koen, Kasuga, 816-8580, Fukuoka, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Masumoto
authors.affiliation: Department of Kinesiology and Nutrition Sciences, University of Nevada, Las Vegas, 4505 Maryland Parkway, Box 453034, Las Vegas, NV, 89154-3034, USA.
authors.forename: Joshua P
authors.initials: JP
authors.lastname: Bailey
authors.affiliation: Department of Kinesiology and Nutrition Sciences, University of Nevada, Las Vegas, 4505 Maryland Parkway, Box 453034, Las Vegas, NV, 89154-3034, USA. john.mercer@unlv.edu.
authors.forename: John A
authors.initials: JA
authors.lastname: Mercer
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D005080:Exercise Test / Q000379:methods; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology*; D005082:Physical Exertion; D012420:Running / Q000502:physiology*; D013550:Swimming / Q000502:physiology*
keywords: Electromyography; Gait; Immersion; Preferred stride frequency