title: Effects of Heavy Strength Training on Running Performance and Determinants of Running Performance in Female Endurance Athletes.
abstract: OBJECTIVE
  The purpose of the current study was to investigate the effects of adding strength training to normal endurance training on running performance and running economy in well-trained female athletes. We hypothesized that the added strength training would improve performance and running economy through altered stiffness of the muscle-tendon complex of leg extensors.
  
  
  METHODS
  Nineteen female endurance athletes [maximal oxygen consumption (VO2max): 53±3 ml∙kg-1∙min-1, 5.8 h weekly endurance training] were randomly assigned to either normal endurance training (E, n = 8) or normal endurance training combined with strength training (E+S, n = 11). The strength training consisted of four leg exercises [3 x 4-10 repetition maximum (RM)], twice a week for 11 weeks. Muscle strength, 40 min all-out running distance, running performance determinants and patellar tendon stiffness were measured before and after the intervention.
  
  
  RESULTS
  E+S increased 1RM in leg exercises (40 ± 15%) and maximal jumping height in counter movement jump (6 ± 6%) and squat jump (9 ± 7%, p < 0.05). This was accompanied by increased muscle fiber cross sectional area of both fiber type I (13 ± 7%) and fiber type II (31 ± 20%) in m. vastus lateralis (p < 0.05), with no change in capillary density in m. vastus lateralis or the stiffness of the patellar tendon. Neither E+S nor E changed running economy, fractional utilization of VO2max or VO2max. There were also no change in running distance during a 40 min all-out running test in neither of the groups.
  
  
  CONCLUSIONS
  Adding heavy strength training to endurance training did not affect 40 min all-out running performance or running economy compared to endurance training only.
authors.affiliation: Section for Sport Science, Lillehammer University College, Lillehammer, Norway.
authors.forename: Olav
authors.initials: O
authors.lastname: Vikmoen
authors.affiliation: Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Truls
authors.initials: T
authors.lastname: Raastad
authors.affiliation: Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Olivier
authors.initials: O
authors.lastname: Seynnes
authors.affiliation: Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Bergstrøm
authors.affiliation: Section for Sport Science, Lillehammer University College, Lillehammer, Norway.
authors.forename: Stian
authors.initials: S
authors.lastname: Ellefsen
authors.affiliation: Section for Sport Science, Lillehammer University College, Lillehammer, Norway.
authors.forename: Bent R
authors.initials: BR
authors.lastname: Rønnestad
mesh_terms: D000328:Adult; D056352:Athletes; D054874:Athletic Performance; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D007866:Leg / Q000502:physiology; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000502:physiology; D010101:Oxygen Consumption; D017847:Patellar Ligament / Q000502:physiology; D010807:Physical Endurance; D055070:Resistance Training; D012420:Running; D012737:Sex Factors; D013997:Time Factors; D055815:Young Adult
chemical_list: D019344:Lactic Acid