title: Quadriceps and hamstring muscle activity during cycling as measured with intramuscular electromyography.
abstract: OBJECTIVE
  The aim of this study was to describe thigh muscle activation during cycling using intramuscular electromyographic recordings of eight thigh muscles, including the biceps femoris short head (BFS) and the vastus intermedius (Vint).
  
  
  METHODS
  Nine experienced cyclists performed an incremental test (start at 170 W and increased by 20 W every 2 min) on a bicycle ergometer either for a maximum of 20 min or to fatigue. Intramuscular electromyography (EMG) of eight muscles and kinematic data of the right lower limb were recorded during the last 20 s in the second workload (190 W). EMG data were normalized to the peak activity occurring during this workload. Statistical significance was assumed at p ≤ 0.05.
  
  
  RESULTS
  The vastii showed a greater activation during the 1st quadrant compared to other quadrants. The rectus femoris (RF) showed a similar activation, but with two bursts in the 1st and 4th quadrants in three subjects. This behavior may be explained by the bi-articular function during the cycling movement. Both the BFS and Vint were activated longer than, but in synergy with their respective agonistic superficial muscles.
  
  
  CONCLUSIONS
  Intramuscular EMG was used to verify muscle activation during cycling. The activation pattern of deep muscles (Vint and BFS) could, therefore, be described and compared to that of the more superficial muscles. The complex coordination of quadriceps and hamstring muscles during cycling was described in detail.
authors.affiliation: The Swedish School of Sport and Health Sciences (GIH), Lidingövägen 1, Office: 1355, (Box: 5626), 114 86, Stockholm, Sweden. julio.cezar@gih.se.|School of Physical Education of the Federal University of Rio Grande do Sul (ESEF/UFRGS), Porto Alegre, Brazil. julio.cezar@gih.se.
authors.forename: Julio Cézar Lima
authors.initials: JC
authors.lastname: da Silva
authors.affiliation: The Swedish School of Sport and Health Sciences (GIH), Lidingövägen 1, Office: 1355, (Box: 5626), 114 86, Stockholm, Sweden.
authors.forename: O
authors.initials: O
authors.lastname: Tarassova
authors.affiliation: The Swedish School of Sport and Health Sciences (GIH), Lidingövägen 1, Office: 1355, (Box: 5626), 114 86, Stockholm, Sweden.|Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.
authors.forename: M M
authors.initials: MM
authors.lastname: Ekblom
authors.affiliation: The Swedish School of Sport and Health Sciences (GIH), Lidingövägen 1, Office: 1355, (Box: 5626), 114 86, Stockholm, Sweden.|Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Andersson
authors.affiliation: The Swedish School of Sport and Health Sciences (GIH), Lidingövägen 1, Office: 1355, (Box: 5626), 114 86, Stockholm, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Rönquist
authors.affiliation: The Swedish School of Sport and Health Sciences (GIH), Lidingövägen 1, Office: 1355, (Box: 5626), 114 86, Stockholm, Sweden.|Department of CLINTEC, Karolinska Institute, Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Arndt
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D004576:Electromyography / Q000379:methods*; D005260:Female; D000070633:Hamstring Muscles / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Cycling; Intramuscular EMG; Muscle activation; Pedaling cycle; Thigh muscles