Andrew D. Moss

A telemetry-based velocometer to measure wheelchair velocity

UNLABELLED The purpose of this paper is to present a telemetry-based velocometer that has the ability to measure wheelchair velocity. Five studies are described which provide measurements of the validity, dynamic response, reliability and resistance of the velocometer. VALIDITY a linear relationship was found when velocity calculated from the velocometer was plotted against three test velocities. The average root mean square deviation (ARMSD) was used to compare velocity calculated from the velocometer with velocity calculated by manual digitising at 200Hz. The ARMSD calculated for each test speed from three trials were 0.06+/-0.01, 0.27+/-0.05 and 0.48+/-0.16 ms(-1) at 1, 5 and 9 ms(-1), respectively. Dynamic response: expressed as a percentage of the average mean trial velocity, the ARMSD for the five acceleration and five deceleration trials were 6.5+/-1.8% and 6.9+/-1.2%, respectively. Reliability was assessed from a comparison between mean trial velocity calculated from velocometer output and the speed of the motor used to spin the wheels. Expressed as a percentage of the mean trial velocity, the mean+/-SD of the differences were 0.00+/-0.17%, for the ten disc wheel trials and 0.00+/-0.41%, for the ten spoke wheel trials. Velocometer resistance calculated as a factor of the mechanical resistance of the wheelchair rear wheel spinning in air were -0.50 and -0.91 N, for the disc and spoke wheel, respectively. Velocometer resistance calculated as a factor of the total mechanical resistance of the wheelchair-wheelchair user system were -1.37 and -1.82 N, for the disc and spoke wheel, respectively.

Muscle tissue oxygenation and VEGF in VO2-matched vibration and squatting exercise

Exposure to vibration has traditionally been associated with compromised perfusion. This study investigated whether blood supply during whole body vibration (WBV), as an exercise modality, is in proportion to the metabolic demand by the contracting musculature. As a secondary aim, serum levels of vascular endothelial growth factor (VEGF) were assessed. Ten young healthy males performed WBV and dynamic shallow squatting (Squat) exercise at comparable levels of oxygen uptake for 3 min. Changes in oxygenated, deoxygenated and total haemoglobin (O2Hb, HHb and tHb, respectively) along with tissue oxygenation index (TOI) were measured continuously before, during and after the exercise by near‐infrared spectroscopy (NIRS, Portamon, Artinis Medical Systems, Zetten, The Netherlands). Vascular endothelial growth factor‐A blood levels before and after exercise were assessed by ELISA. Oxygen uptake was comparable in Squat and WBV (11·4 and 10·7 ml kg−1 min−1), respectively, P = 0·49), as were all other cardiopulmonary variables. Near‐infrared spectroscopy data were found to be non‐stationary during and shortly after WBV, but stationary in Squat. There was an increase in O2Hb and TOI, and a decrease in HHb during the first 30 s of WBV, but no significant change was observed during Squat. No group difference was found in VEGF serum levels. These results suggest that oxygen supply during WBV is sufficient, and oxygenation is even enhanced during the first approximately 30 s. Most likely, the transient response is because of local vascular regulatory mechanisms and due to muscle contraction mechanics. This might become clinically relevant under pathological conditions, e.g. in vascular disorders.

Growth hormone deficiency after childhood bone marrow transplantation with total body irradiation: interaction with adiposity and age

Bone marrow transplantation with total body irradiation (BMT/TBI) has adverse effects on growth, growth hormone status and adiposity. We investigated the GH–IGF‐I axis in relation to adiposity.

The influence of angiotensin converting enzyme and bradykinin receptor B2 gene variants on voluntary fluid intake and fluid balance in healthy men during moderate-intensity exercise in the heat

Angiotensin converting enzyme (ACE) and bradykinin receptor B2 (B2R) genetic variation may affect thirst because of effects on angiotensin II production and bradykinin activity, respectively. To examine this, 45 healthy Caucasian men completed 60 min of cycle exercise at 62% ± 5% peak oxygen uptake in a room heated to 30.5 ± 0.3 °C with ad libitum fluid intake. Blood samples were collected pre-, mid-, and immediately post-cycle. Fluid intake, body mass loss (BML), sweat loss (determined via changes in body mass and fluid intake), and thirst sensation were recorded. All participants were genotyped for the ACE insert fragment (I) and the B2R insert sequence (P). Participants were homozygous for the wild-type allele (WW or MM), heterozygous (WI or MP) or homozygous for the insert (II or PP). No differences between genotype groups were found in mean (±SD) voluntary fluid intake (WW: 613 ± 388, WI: 753 ± 385, II: 862 ± 421 mL, p = 0.31; MM: 599 ± 322, MP: 745 ± 374, PP: 870 ± 459 mL, p = 0.20), percentage BML or any other fluid balance variables for both the ACE and B2R genes, respectively. Mean thirst perception in the B2R PP group, however, was higher (p < 0.05) than both MM and MP at 30, 45, and 60 min. In conclusion, the results of this study suggest that voluntary fluid intake and fluid balance in healthy men performing 60 min of moderate-intensity exercise in the heat are not predominantly influenced by ACE or B2R genetic variation.