Proteostasis and ageing: insights from long-lived mutant mice

The global increase in life expectancy is creating significant medical, social and economic challenges to current and future generations. Consequently, there is a need to identify the fundamental mechanisms underlying the ageing process. This knowledge should help develop realistic interventions capable of combatting age-related disease, and thus improving late-life health and vitality. While several mechanisms have been proposed as conserved lifespan determinants, the loss of proteostasis- where proteostasis is defined here as the maintenance of the proteome- appears highly relevant to both ageing and disease. Several studies have shown that multiple proteostatic mechanisms, including the endoplasmic reticulum (ER)-induced unfolded protein response (UPR), the ubiquitin-proteasome system (UPS) and autophagy, all appear indispensable for longevity in many long-lived invertebrate mutants. Similarly, interspecific comparisons suggest that proteostasis may be an important lifespan determinant in vertebrates. Over the last 20 years a number of long-lived mouse mutants have been described, many of which carry single-gene mutations within the growth-hormone, insulin/IGF-1 or mTOR signalling pathways. However, we still do not know how these mutations act mechanistically to increase lifespan and healthspan, and accordingly whether mechanistic commonality occurs between different mutants. Recent evidence supports the premise that the successful maintenance of the proteome during ageing may be linked to the increased lifespan and healthspan of long-lived mouse mutants

KINEMATIC CHARACTERISTICS OF ALIGNMENT IN ACROBATIC ATHLETES

The purpose of this study was to determine if an underlying structure defining an ‘aligned’ body could be identified in acrobatic athletes, and to assess extreme examples of this structure for specific kinematic differences. Twenty-five male and female competitive gymnasts and divers were assessed for body segment alignment in a straight-standing position. Passive reflective markers were placed on the skin surface covering a variety of anatomical landmarks along the appendages and torso, including the spine. Athletes were instructed to assume the ‘straightest body position possible’ with their arms overhead and eyes forward. An HD digital camcorder recorded this position for approximately 5s. The video was digitized for various angular positions of the upper and lower extremities and the torso. Hierarchical cluster analyses revealed 4 clusters of athletes based on the kinematic variables. Athletes comprising the two most distant clusters (labelled ‘best’ and ‘worst’ with regard to alignment variables) were selected for further comparison. Discriminant and logistic regression identified pelvic tilt relative to vertical and forward head angle as the variables accounting for the most variance between the two groups. Independent t-tests revealed that athletes from the ‘best’ cluster were characterized by a more vertically aligned trunk, upper extremity-sternum, upper extremity-trunk, lower limb, and pelvic tilt, a more forward head position and smaller cervicothoracic angle. Identification of kinematic characteristics associated with an aligned body can help direct coaching and talent identification efforts for achievement of this position

VERTICAL IMPACT FORCE AND LOADING RATE ON THE GYMNASTICS TABLE VAULT

The purpose of this study was to determine the effect of low and high intensity impact forces on the average loading rate during a forward handspring vault. Peak force, time to peak and impulse were used to characterize the impact vertical force during a vault performed by 12 female gymnasts. Reaction forces from right and left hands were measured at 500 Hz with two PASCO portable force platforms fixed to the vault table surface. Force data were split in two groups: Low intensity (LI: peak forces 0.7 BW). Significant differences (

TEMPORAL, FORCE AND POSTURAL ANALYSIS OF RELEVÉ EN POINTE IN NOVICE AND INTERMEDIATE DANCERS

This study compares temporal, vertical force and postural sway variables between novice and intermediate dancers performing echappé relevé en pointe (a); to determine the influence of experience on intra-individual variability on the aforementioned performance parameters (b). Six trials performed by four novice and four intermediate dancers on a force platform were analysed. Large differences between the two groups of dancers were observed in the duration of the transition phase from the plié to the en pointe and in the length of sway path of the CoP during the en pointe phase. High loading rate was recorded when landing en pointe. Both groups of dancers showed a relatively large rate of intra-individual variability that can be seen as a task-relevant learning facilitator factor

Disentangling the effect of dietary restriction on mitochondrial function using recombinant inbred mice

Dietary restriction (DR) extends lifespan and healthspan in many species, but precisely how it elicits its beneficial effects is unclear. We investigated the impact of DR on mitochondrial function within liver and skeletal muscle of female ILSXISS mice that exhibit strain-specific variation in lifespan under 40% DR. Strains TejJ89 (lifespan increased under DR), TejJ48 (lifespan unaffected by DR) and TejJ114 (lifespan decreased under DR) were studied following 10 months of 40% DR (13 months of age). Oxygen consumption rates (OCR) within isolated liver mitochondria were unaffected by DR in TejJ89 and TejJ48, but decreased by DR in TejJ114. DR had no effect on hepatic protein levels of PGC-1a, TFAM, and OXPHOS complexes IV. Mitonuclear protein imbalance (nDNA:mtDNA ratio) was unaffected by DR, but HSP90 protein levels were reduced in TejJ114 under DR. Surprisingly hepatic mitochondrial hydrogen peroxide (H2O2) production was elevated by DR in TejJ89, with total superoxide dismutase activity and protein carbonyls increased by DR in both TejJ89 and TejJ114. In skeletal muscle, DR had no effect on mitochondrial OCR, OXPHOS complexes or mitonuclear protein imbalance, but H2O2 production was decreased in TejJ114 and nuclear PGC-1a increased in TejJ89 under DR. Our findings indicate that hepatic mitochondrial dysfunction associated with reduced lifespan of TejJ114 mice under 40% DR, but similar dysfunction was not apparent in skeletal muscle mitochondria. We highlight tissue-specific differences in the mitochondrial response in ILSXISS mice to DR, and underline the importance and challenges of exploiting genetic heterogeneity to help understand mechanisms of ageing

Kinetic and Kinematic Asymmetries during Unloaded and Loaded Static Jumps

Abstract available in the Annual coaches and Sport Science College

KINEMATIC ANALYSIS OF MEN BOBSLED PUSH STARTS

The purpose of this study was to provide a descriptive analysis of selected kinematic variables associated with the push start for brakemen in the two-man bobsled. Eleven male bobsledders served as subjects for this study. The subjects were videotaped at 120 Hz during competition at the Lake Placid, NY bobsled track as they were competing for positions on the men’s 2004 National Bobsled Team. Selected groups of variables measured at specific events in this study included step length, frequency, and foot contact time; COM velocity; and trunk, knee, and elbow angles. A relationship of 0.63 was determined between start time and finish time; an exploratory correlational analysis between start time and COM velocity at 2nd step take-off (TO) was -0.63. Start time is of critical importance in determining final race time

Exploratory investigation of impact loads during the forward handspring vault

The purpose of this study was to examine kinematic and kinetic differences in low and high intensity hand support impact loads during a forward handspring vault. A high-speed video camera (500 Hz) and two portable force platforms (500 Hz) were installed on the surface of the vault table. Two-dimensional analyses were conducted on 24 forward handspring vaults performed by 12 senior level, junior Olympic program female gymnasts (16.9 ±1.4 yr; body height 1.60 ±0.1 m; body mass 56.7 ±7.8 kg). Load intensities at impact with the vault table were classified as low (peak force 0.8 x body weight). These vaults were compared via crucial kinetic and kinematic variables using independent t-tests and Pearson correlations. Statistically significant (p < 0.001) differences were observed in peak force (t(24) = 4.75, ES = 3.37) and time to peak force (t(24) = 2.07, ES = 1.56). Statistically significant relationships between the loading rate and time to peak force were observed for high intensity loads. Peak force, time to peak force, and a shoulder angle at impact were identified as primary variables potentially involved in the determination of large repetitive loading rates on the forward handspring vault

CHANGES IN PEAK ACCELERATION IN THE SNATCH ACROSS MULTIPLE ATTEMPTS IN TRAINING: A CASE STUDY

Accelerometers are devices that have been recently used to assess the performance of weightlifters in training. This case study used vertical acceleration data to assess multiple snatch attempts in a single lifter during a training session. The lifter exhibited variability in a number of measures, including peak acceleration and peak velocity. The measures calculated from the acceleration-time data did not show consistent trends between made and missed lifts. More work is needed identify variables of interest for snatch performance