PED/PEA-15 Controls Fibroblast Motility and Wound Closure by ERK1/2-Dependent Mechanisms

Cell migration is dependent on the control of signaling events that play significant roles in creating contractile force and in contributing to wound closure. We evaluated wound closure in fibroblasts from mice overexpressing (TgPED) or lacking ped/pea-15 (KO), a gene overexpressed in patients with type 2 diabetes. Cultured skin fibroblasts isolated from TgPED mice showed a significant reduction in the ability to recolonize wounded area during scratch assay, compared to control fibroblasts. This difference was observed both in the absence and in the presence of mytomicin C, an inhibitor of mitosis. In time-lapse experiments, TgPED fibroblasts displayed about twofold lower velocity and diffusion coefficient, as compared to controls. These changes were accompanied by reduced spreading and decreased formation of stress fibers and focal adhesion plaques. At the molecular level, TgPED fibroblasts displayed decreased RhoA activation and increased abundance of phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2). Inhibition of ERK1/2 activity by PD98059 restored RhoA activation, cytoskeleton organization and cell motility, and almost completely rescued wound closure of TgPED fibroblasts. Interestingly, skin fibroblasts isolated from KO mice displayed an increased wound closure ability. In vivo, healing of dorsal wounds was delayed in TgPED and accelerated in KO mice. Thus, PED/PEA-15 may affect fibroblast motility by a mechanism, at least in part, mediated by ERK1/2. J. Cell. Physiol. 227: 2106–2116, 2012. © 2011 Wiley Periodicals, Inc

Combined cycle and run performance is maximised when the cycle is completed at the highest sustainable intensity

The aim of this study was to determine the effect of cycle intensity on subsequent running performance and combined cycle–run (CR) performance. Seven triathletes undertook a cycling graded exercise test to exhaustion, an isolated 500-kJ cycle time trial (CTT) and an isolated 5-km running time trial. Then they performed a series of CR tests, at various cycle intensities, followed by an all-out, 5-km run. The CR tests were separated into four categories based on the percentage of the CTT at which the cycle was performed (CR 81–85%, CR 86–90%, CR 91–95%, and CR 96–100%). Running performance was slower during CR 96–100% compared to CR 81–85% and CR 86–90% (20:45 ± 1:19 vs. 19:56 ± 0:40 and 19:46 ± 0:49 min; P 0.05). CR performance was maximised during CR 96–100% when compared to CR 81–85, CR 86–90 and CR 91–95% (56:37 ± 4:04 vs. 62:40 ± 5:30, 59:53 ± 4:41 and 58:29 ± 4:40 min; P < 0.05). The results suggest that combined cycle and run performance is maximised when the cycle is completed at the highest sustainable intensity

The effects of high-intensity interval training in well-trained rowers

Purpose: Several recent studies have reported substantial performance and physiological gains in well-trained endurance runners, swimmers, and cyclists following a period of high-intensity interval training (HIT). The aim of the current study was to compare traditional rowing training (CT) to HIT in well-trained rowers. Methods: Subjects included 5 male and 5 female rowers (mean +/- SD; age = 19 +/- 2 y; height = 176 +/- 8 cm; mass = 73.7 +/- 9.8 kg; VO(2peak) = 4.37 +/- 1.08 L.min(-1)). Baseline testing included a 2000-m time trial and a maximal exercise test to determine VO(2peak), 4-min all-out power, and 4 mmol.L(-1) blood lactate threshold. Following baseline testing, rowers were randomly allocated to HIT or CT, which they performed seven times over a 4-wk period. The HIT involved 8 x 2.5-min intervals at 90% of the velocity maintained at VO(2peak), with individual recoveries returning to 70% of the subjects' maximal heart rate between intervals. The CT intensity consisted of workloads corresponding to 2 and 3 mmol.L(-1) blood lactate concentrations. On completion of HIT or CT, rowers repeated the testing performed at baseline and were then allocated to the alternative training program and completed a crossover trial. Results: HIT produced greater improvements in 2000-m time (1.9 +/- 0.9%; mean +/- SD), 2000-m power (5.8 +/- 3.0%), and relative VO(2peak) (7.0 +/- 6.4%) than CT. Conclusion: Four weeks of HIT improves 2000-m time-trial performance and relative VO(2peak) in competitive rowers, more than a traditional approach