title: In vivo and in vitro evidence that intrinsic upper- and lower-limb skeletal muscle function is unaffected by ageing and disuse in oldest-old humans.
abstract: OBJECTIVE
  To parse out the impact of advanced ageing and disuse on skeletal muscle function, we utilized both in vivo and in vitro techniques to comprehensively assess upper- and lower-limb muscle contractile properties in 8 young (YG; 25 ± 6 years) and 8 oldest-old mobile (OM; 87 ± 5 years) and 8 immobile (OI; 88 ± 4 years) women.
  
  
  METHODS
  In vivo, maximal voluntary contraction (MVC), electrically evoked resting twitch force (RT), and physiological cross-sectional area (PCSA) of the quadriceps and elbow flexors were assessed. Muscle biopsies of the vastus lateralis and biceps brachii facilitated the in vitro assessment of single fibre-specific tension (Po).
  
  
  RESULTS
  In vivo, compared to the young, both the OM and OI exhibited a more pronounced loss of MVC in the lower limb [OM (-60%) and OI (-75%)] than the upper limb (OM = -51%; OI = -47%). Taking into account the reduction in muscle PCSA (OM = -10%; OI = -18%), only evident in the lower limb, by calculating voluntary muscle-specific force, the lower limb of the OI (-40%) was more compromised than the OM (-13%). However, in vivo, RT in both upper and lower limbs (approx. 9.8 N m cm(-2) ) and Po (approx. 123 mN mm(-2) ), assessed in vitro, implies preserved intrinsic contractile function in all muscles of the oldest-old and were well correlated (r = 0.81).
  
  
  CONCLUSIONS
  These findings suggest that in the oldest-old, neither advanced ageing nor disuse, per se, impacts intrinsic skeletal muscle function, as assessed in vitro. However, in vivo, muscle function is attenuated by age and exacerbated by disuse, implicating factors other than skeletal muscle, such as neuromuscular control, in this diminution of function.
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.|Department of Neurological, and Movement Sciences, University of Verona, Verona, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Venturelli
authors.affiliation: Division of Radiology and Imaging, City of Verona Diagnostic Center, Verona, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Saggin
authors.affiliation: Mons. Mazzali Foundation, Mantova, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Muti
authors.affiliation: DAHFMO Unit of Histology and Medical Embryology, Sapienza University, Rome, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Naro
authors.affiliation: Department of Biomedical Sciences, University of Padova, Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Cancellara
authors.affiliation: Department of Biomedical Sciences, University of Padova, Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Toniolo
authors.affiliation: Department of Neurological, and Movement Sciences, University of Verona, Verona, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Tarperi
authors.affiliation: Department of Neurological, and Movement Sciences, University of Verona, Verona, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Calabria
authors.affiliation: Division of Geriatrics, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA.|Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA.|Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Richardson
authors.affiliation: Department of Biomedical Sciences, University of Padova, Padova, Italy.|CNR (Consiglio Nazionale delle Ricerche), Institute of Neuroscience, Padua, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Reggiani
authors.affiliation: Department of Neurological, and Movement Sciences, University of Verona, Verona, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Schena
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D000369:Aged, 80 and over; D000375:Aging; D004550:Elbow / Q000502:physiology*; D005121:Extremities / Q000502:physiology*; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology; D055815:Young Adult
keywords: in vitro; in vivo; oldest-old; sarcopenia