title: Does a single session of high-intensity interval training provoke a transient elevated risk of falling in seniors and adults?
abstract: BACKGROUND
  Balance and strength training can reduce seniors' fall risk up to 50%. Available evidence suggests that acute bouts of neuromuscular and endurance exercise deteriorate postural control. High-intensity endurance training has been successfully applied in different populations. Thus, it seemed valuable to examine the acute effects of high-intensity interval training (HIIT) on neuromuscular performance in seniors and young adults.
  
  
  OBJECTIVE
  The acute impact of a HIIT session on balance performance and muscle activity after exercise cessation and during post-exercise recovery was examined in young and old adults. We intended to investigate whether a transient exercise-induced fall-risk may occur in both groups.
  
  
  METHODS
  20 healthy seniors (age 70 (SD 4) years) and young adults (age 27 (SD 3) years) were examined on 3 days. After exhaustive ramp-like treadmill testing in order to determine maximal heart rate (HRmax) on the first day, either a 4 × 4 min HIIT at 90% of HRmax or a control condition (CON) was randomly performed on the second and third day, respectively. Balance performance (postural sway) was assessed during single limb stance with open eyes (SLEO) and double limb stance with closed eyes (DLEC). EMG was recorded for the soleus (SOL), anterior tibialis (TIB), gastrocnemius (GM) and peroneus longus (PL) muscles at the dominant leg. All measures were collected before, immediately as well as 10, 30 and 45 min after HIIT and CON, respectively.
  
  
  RESULTS
  Compared to CON, HIIT induced significant increases of postural sway immediately after exercise cessation during SLEO in both groups (adults: p < 0.001, Δ = +25% sway; seniors: p = 0.007, Δ = +15% sway). Increased sway during DLEC was only found for seniors immediately and 10 min after HIIT (post: p = 0.003, Δ = +14% sway, 10 min post: p = 0.004, Δ = +18% sway). Muscle activity was increased during SLEO for TIB until 10 min post in seniors (0.008 < p < 0.03) and immediately after HIIT in adults (p < 0.001).
  
  
  CONCLUSIONS
  HIIT training may cause an acute 'open-fall-window' with a transient impairment of balance performance for at least 10 min after exercise cessation in both groups. Occluded vision in seniors seems to prolong this period up to 30 min. Thus, the advantage of HIIT with regard to time efficiency seems debatable when considering transient HIIT-induced impairments of neuromuscular function.
authors.affiliation: Department of Sport, Exercise and Health, University of Basel, Basel, Switzerland.
authors.forename: Lars
authors.initials: L
authors.lastname: Donath
authors.forename: Eduard
authors.initials: E
authors.lastname: Kurz
authors.forename: Ralf
authors.initials: R
authors.lastname: Roth
authors.forename: Henner
authors.initials: H
authors.lastname: Hanssen
authors.forename: Arno
authors.initials: A
authors.lastname: Schmidt-Trucksäss
authors.forename: Lukas
authors.initials: L
authors.lastname: Zahner
authors.forename: Oliver
authors.initials: O
authors.lastname: Faude
mesh_terms: D000058:Accidental Falls; D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D012306:Risk; D055815:Young Adult