title: Relationships between decreasing force and muscle oxygenation kinetics during sustained static gripping.
abstract: The purposes of this study were to clarify the kinetics of muscle oxygenation (Oxy-Hb, Deoxy-Hb) by near infrared spectroscopy (NIR) in the decreasing force phase, especially the pre- and post-phases of the inflection point, in sustained maximal static gripping (SSG), and to examine the relationship between kinetics of muscle oxygenation and force-decreasing parameters. The experiment was conducted on 20 male subjects aged 15-18 years. The time at the lowest Oxy-Hb value (20.5+/-5.5 s) significantly correlated with the decreasing times of forces of 40, 60 and 80% of maximal voluntary contraction (MVC), and the rate of decreasing force for 0-1 min (r=.60,.53,.49, and -.63 respectively). These parameters reflect the decreasing force based on the oxygenation deficiency into the muscle with the obstruction of the blood flow. The time of reaching the highest Deoxy-Hb value (46.8+/-15.0 s) and the regression coefficient in the Deoxy-Hb decreasing phase correlated significantly with the decrement for 1-2 min. This parameter evaluates the phase where resumption of the blood flow began, and Deoxy-Hb in the tissue was eliminated. The inflection point of the gripping force is related to the time at the highest Deoxy-Hb, and reflects the beginning and the resumption of the blood flow. The decrement for 2-3 min and the regression coefficient of post-inflection point evaluate the steady state phase of force decreasing, in which oxygen is sufficiently supplied to active muscles.
authors.affiliation: Fukui National College of Technology, Japan. yamaji@fukui-nct.ac.jp
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Yamaji
authors.forename: Shinichi
authors.initials: S
authors.lastname: Demura
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nagasawa
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Nakada
mesh_terms: D000293:Adolescent; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010807:Physical Endurance / Q000502:physiology; D019265:Spectroscopy, Near-Infrared
chemical_list: D010100:Oxygen