title: Dynamic assessment of ventilatory efficiency during recovery from peak exercise to enhance cardiopulmonary exercise testing.
abstract: BACKGROUND
  While cardiopulmonary exercise testing (CPX) assessment is generally regarded as an optimal means to assess functional capacity in heart failure (HF) patients, strength parameters are omitted. CPX indices collected in recovery may provide additional insight regarding function, including strength.
  
  
  METHODS
  We performed a cross-sectional controlled study. Systolic HF patients (aged ≥ 50 years) and age-matched controls were assessed using CPX and strength evaluations. Standard CPX indices were assessed during exercise (peak oxygen consumption [VO2], first ventilatory threshold [1stVT], and ventilatory efficiency [VE/VCO2 slope]) as well as indices at 1-minute recovery (1 min VO2, 1 min VE/VCO2, and 1 min heart rate recovery [HRR]) and differences between peak and 1-minute recovery (ΔVO₂ and ΔVE/VCO₂). Lower extremity strength was evaluated using the 1-repetition maximum (1RM) and power.
  
  
  RESULTS
  Seventy adults (31 HF; 39 controls), mean age 66.2 ± 9.7 years were evaluated. Peak VO2 (15.4 ± 4.2 versus 23.4 ± 6.6 mlO₂·kg(-1)·min(-1), p < 0.0001) and 1stVT (10.9 ± 2.1 versus 14.4 ± 4.0 mlO₂·kg(-1)·min(-1), p < 0.0001) were diminished in HF versus controls and VE/VCO2 slope was increased (42.3 ± 12.2 versus 35.4 ± 8.3, p < 0.01). HF patients had reduced 1 minVO₂ (13.1 ± 2.9 versus 16.3 ± 3.7 mlO₂·kg(-1)·min(-1), p < 0.0001), 1 min HRR (6.7 ± 11.4 versus 12.4 ± 7.6 beats, p < 0.02), and ΔVO₂ (2.43 ± 2.3 versus 7.3 ± 5.0 mlO₂·kg(-1)·min(-1), p < 0.0001) as well as increased 1 min VE/VCO2 (37 ± 7.5 versus 31.5 ± 4.4, p < 0.001) and ΔVE/VCO₂ (1.17 ± 3.0 versus -0.5 ± 1.3, p < 0.0001). Strength parameters were relatively lower in HF. While CPX exercise parameters correlated with strength, stronger correlations were observed between CPX recovery parameters and strength.
  
  
  CONCLUSIONS
  CPX recovery indices corroborate disease-specific aerobic differences and distinguish differences in strength. Recovery ventilatory efficiency enhances CPX's value as a comprehensive physical function tool.
authors.affiliation: New England Geriatric Research, Education, and Clinical Center, VA Boston Healthcare System, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Zavin
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
authors.forename: Jacob
authors.initials: J
authors.lastname: Joseph
authors.forename: Kelly
authors.initials: K
authors.lastname: Allsup
authors.forename: Karla
authors.initials: K
authors.lastname: Daniels
authors.forename: P Christian
authors.initials: PC
authors.lastname: Schulze
authors.forename: Stewart
authors.initials: S
authors.lastname: Lecker
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Forman
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance; D006333:Heart Failure / Q000175:diagnosis* / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D012123:Pulmonary Ventilation; D020127:Recovery of Function; D013997:Time Factors