F-29: Free Communication/Poster – Muscle: Fatigue and Oxygen Kinetics: FRIDAY, JUNE 3, 2005 2:00 PM - 5:00 PM, ROOM: Ryman C2
During recent years the use of non-invasive measurements of muscle oxygen saturation (O2sat%) using near infrared spectroscopy (NIRS) has increased considerably. Repeated measurements are commonly employed for monitoring treatment in clinical assessments and for experimental designs in sports and occupational venues. However reproducibility data of O2sat% are sparse, and those existing tend to suggest that the reliability may be muscle related; whether gender plays a role is virtually unknown.
To determine the inter-day reliability of O2sat% of the forearm extensor carpi radialis (ECR) and trapezius (trap) muscles of males and females. These muscles were chosen because of their incidence in work-related musculoskeletal disorders.
On two occasions, separated by 3–5 days, NIRS probes were placed by the same individual on the ECR and trap of 12 male and 12 female college students (19–28 yrs). Probe positions were referenced to bony landmarks of the elbow and the cervix, and a skin mark was made on the 1st occasion to facilitate placement on the 2nd occasion. A 25-mm probe (i.e. indicating the distance between the light transmitter and detector, Inspectra 325, Hutchinson Technology) enabling a penetration depth of 23 mm, was used. Recordings were made while subjects sat quietly for 5 min. To determine the effect of probe size on O2sat%, a 12-mm probe (11 mm penetration depth) was used for an additional group of female subjects (n=9) of the same age range and for the same inter-day time frame; however, only ECR O2sat% was recorded for this group.
When using the 25-mm probe, males showed about a 15% greater O2sat% than females for both the ECR and the trap on each occasion. For testing between occasions, intra-class correlation (ICC) values were high for the trap for both males (0.75) and females (0.90). For the ECR, ICC was high for males (0.74), but moderate for females (0.44). When using the 12-mm probe, the magnitude of ECR O2sat% was the same as for the 25-mm probe. However, ICC for this female group was improved to a higher rating (0.80).
While probe size, i.e. penetration depth, is not accountable for our gender differences in O2sat% magnitudes, the higher inter-day reliability for the 12-mm probe indicates that this smaller probe is recommended for ECR O2sat% measurements of females