Dean V. Sculley

Periodontal disease is associated with lower antioxidant capacity in whole saliva and evidence of increased protein oxidation.

The aim of this cohort study was to determine whether periodontitis and gingivitis are associated with impaired salivary antioxidant status and increased oxidative injury. One hundred and twenty-nine patients attending a routine dental check-up were recruited for the study. Periodontal disease status was characterized using the Community Periodontal Index of Treatment Needs (CPITN) system. Total salivary antioxidant capacity and salivary ascorbate, urate and albumin were determined in a sample of whole unstimulated saliva. Protein carbonyl concentrations were determined as an index of oxidative injury. Patients in the lowest tertile of CPITN score exhibited decreased salivary delivery of antioxidants and specifically urate than patients in the upper tertile. Poor periodontal health was associated with increased concentrations of protein carbonyls in saliva. Women had significantly lower total antioxidant status than men, regardless of periodontal health. Periodontal disease is associated with reduced salivary antioxidant status and increased oxidative damage within the oral cavity.

Exposure to undernutrition in fetal life determines fat distribution, locomotor activity and food intake in ageing rats

Objective:To assess the long-term impact of undernutrition during specific periods of fetal life, upon central adiposity, control of feeding behaviour and locomotor activity.Design:Pregnant rats were fed a control or low-protein (LP) diet, targeted to early (LPE), mid (LPM) or late (LPL) pregnancy or throughout gestation (LPA). The offspring were studied at 9 and 18 months of age.Measurements:Adiposity was assessed by measuring weight of abdominal fat depots relative to body weight. Locomotor activity was assessed using an infrared sensor array system in both light and dark conditions. Hypothalamic expression of mRNA for galanin and the galanin 2 receptor (Gal2R) was determined using real-time PCR.Results:At 9 months, male rats exposed to LP in utero had less fat in the gonadal depot, but were of similar body weight to controls. By 18 months, the males of groups LPA and LPM had more abdominal and less subcutaneous fat. Females deposited more fat centrally than males between 9 and 18 months of age, and this was more marked in groups LPA and LPL. Food intake was greater in LPM males. Among females hypophagia was noted in groups LPA and LPL. Expression of galanin and Gal2R were unaffected by maternal diet. Total locomotor activity was reduced in LPE males and all LP females in the light but not in the dark.Conclusion:Locomotor activity and feeding behaviour in aged rats are subject to prenatal programming influences. Fetal undernutrition does not programme obesity in rats without postnatal dietary challenge.

Salivary antioxidants and periodontal disease status

Periodontal disease is a common chronic adult condition. The bacterium Porphyromonas gingivalis has been implicated in the aetiology of this disease, which causes destruction of the connective tissue and bone around the root area of the tooth. It has been observed that invading P. gingivalis bacteria trigger the release of cytokines such as interleukin 8 and tumour necrosis factor a, leading to elevated numbers and activity of polymorphonucleocytes (PMN). As a result of stimulation by bacterial antigens, PMN produce the reactive oxygen species (ROS) superoxide via the respiratory burst as part of the host response to infection. Patients with periodontal disease display increased PMN number and activity. It has been suggested that this proliferation results in a high degree of ROS release, culminating in heightened oxidative damage to gingival tissue, periodontal ligament and alveolar bone. Antioxidant constituents in plasma have been well-documented, being chiefly ascorbate, albumin and urate, and these are known to display sensitivity to dietary antioxidant intakes. The concentration of antioxidants in saliva does not appear to mirror those of plasma. The extent of dietary influence upon salivary antioxidant status is unclear. Urate is the predominant salivary antioxidant, with albumin and ascorbate providing minor contributions. Previous research has found reduced salivary antioxidant activity in patients suffering from periodontal disease. An improved understanding of the role antioxidants play in periodontitis, and the influence of nutrition on antioxidant status, may lead to a possible nutritional strategy for the treatment of periodontal disease.

The association between birthweight and longevity in the rat is complex and modulated by maternal protein intake during fetal life.

Maternal protein restriction in rat pregnancy has been suggested to reduce lifespan of the resulting offspring by inducing fetal growth retardation, followed by postnatal catch‐up growth. We tested the hypothesis that lifespan could be programmed in both males and females by exposure to undernutrition at specific stages of fetal development. Protein restriction throughout gestation significantly reduced lifespan in both males and females. Low birthweight increased longevity, whilst rapid postnatal growth had a detrimental effect. There was no evidence that undernutrition programmed lifespan through oxidative processes in the major organs. Fetal programming is an important contributor to the ageing process.

Programming of hepatic antioxidant capacity and oxidative injury in the ageing rat

Exposure to undernutrition in fetal life increases the susceptibility of humans and animals to major disease states in adult life. Studies of rodents exposed to protein restriction during fetal life indicate that lifespan is reduced, a finding that is the opposite of the well-documented improvement in longevity noted with post-weaning caloric restriction. The maternal low-protein (MLP) model of rat pregnancy therefore provides a suitable vehicle to consider how nutrition in fetal life may programme mechanisms of ageing. Pregnant rats were fed control (n = 7) or MLP diet (n = 7) throughout pregnancy. At birth, increased oxidation of hepatic proteins was noted, and this appeared related to activity of glutathione reductase. Older offspring were studied at 4, 16, 30 and 44 weeks of age and analyses revealed that MLP exposure in utero produced sex-specific differences in oxidant:antioxidant balance. In male offspring, MLP increased protein carbonyl concentrations in the liver (P = 0.013) and increased glutathione peroxidase activity (P = 0.018). These programmed changes were absent in the female offspring. The data support the hypothesis that reduced lifespan in rats subject to prenatal protein restriction is a consequence of enhanced oxidative processes promoting apoptosis and loss of tissue function. Mechanisms of ageing appear to be subject to nutritional programming during early development.

Fetal exposure to a maternal low-protein diet during mid-gestation results in muscle-specific effects on fibre type composition in young rats

This study assessed the impact of reduced dietary protein during specific periods of fetal life upon muscle fibre development in young rats. Pregnant rats were fed a control or low-protein (LP) diet at early (days 0-7 gestation, LPEarly), mid (days 8-14, LPMid), late (days 15-22, LPLate) or throughout gestation (days 0-22, LPAll). The muscle fibre number and composition in soleus and gastrocnemius muscles of the offspring were studied at 4 weeks of age. In the soleus muscle, both the total number and density of fast fibres were reduced in LPMid females (P = 0.004 for both, Diet x Sex x Fibre type interactions), while both the total number and density of glycolytic (non-oxidative) fibres were reduced in LPEarly, LPMid and LPLate (but not LPAll) offspring compared with controls (P < 0.001 for both, Diet x Fibre type interaction). In the gastrocnemius muscle, only the density of oxidative fibres was reduced in LPMid compared with control offspring (P = 0.019, Diet x Fibre type interaction), with the density of slow fibres being increased in LPAll males compared with control (P = 0.024, Diet x Sex x Fibre type interaction). There were little or no effects of maternal diet on fibre type diameters in the two muscles. In conclusion, a maternal low-protein diet mainly during mid-pregnancy reduced muscle fibre number and density in 4-week-old rats, but there were muscle-specific differences in the fibre types affected.

Ice slurry ingestion during cycling improves Olympic distance triathlon performance in the heat

Abstract This study investigated the effect of ice slurry ingestion during a triathlon on intragastric temperature and 10 km running performance in the heat. Nine well-trained male triathletes performed two randomised trials of a simulated Olympic distance triathlon in hot conditions (32–34°C). Exercise intensity during the swim (1500 m) and cycle (1 hr) legs was standardised, and the 10 km run leg was a self-paced time trial. During the cycle leg, either 10 g · kgBM−1 of ice slurry (< 1°C) or room temperature fluid (32–34°C) was ingested. In the run leg of the ice slurry trial, performance time (43.4 ± 3.7 vs. 44.6 ± 4.0 min; P = 0.03), intragastric temperature (at 1.5 km; 35.5 ± 1.2 vs. 37.5 ± 0.4°C; P = 0.002) and perceived thermal stress (at 5 km; 73 ± 9 vs. 80 ± 7 mm; P = 0.04) were significantly lower. Oxygen consumption was significantly higher in the ice trial between 9.5–10 km (52.4 ± 3.4 vs. 47.8 ± 5.4 mL · kg−1 · min−1; P = 0.04). The results suggest ice slurry ingestion was an effective ergogenic aid for triathlon running performance in the heat. The attenuation of intragastric temperature and perceived thermal stress were likely contributors to the self-selection of a higher running intensity and improved performance time.

Running performance and thermal sensation in the heat are improved with menthol mouth rinse but not ice slurry ingestion

The purpose of this study was to compare the effects of a cooling strategy designed to predominately lower thermal state with a strategy designed to lower thermal sensation on endurance running performance and physiology in the heat. Eleven moderately trained male runners completed familiarization and three randomized, crossover 5‐km running time trials on a non‐motorized treadmill in hot conditions (33 °C). The trials included ice slurry ingestion before exercise (ICE), menthol mouth rinse during exercise (MEN), and no intervention (CON). Running performance was significantly improved with MEN (25.3 ± 3.5 min; P = 0.01), but not ICE (26.3 ± 3.2 min; P = 0.45) when compared with CON (26.0 ± 3.4 min). Rectal temperature was significantly decreased with ICE (by 0.3 ± 0.2 °C; P < 0.01), which persisted for 2 km of the run and MEN significantly decreased perceived thermal sensation (between 4 and 5 km) and ventilation (between 1 and 2 km) during the time trial. End‐exercise blood prolactin concentration was elevated with MEN compared with CON (by 25.1 ± 24.4 ng/mL; P = 0.02). The data demonstrate that a change in the perception of thermal sensation during exercise from menthol mouth rinse was associated with improved endurance running performance in the heat. Ice slurry ingestion reduced core temperature but did not decrease thermal sensation during exercise or improve running performance.

Physical performance during high-intensity resistance exercise in normoxic and hypoxic conditions

Abstract Scott, BR, Slattery, KM, Sculley, DV, Hodson, JA, and Dascombe, BJ. Physical performance during high-intensity resistance exercise in normoxic and hypoxic conditions. J Strength Cond Res 29(3): 807–815, 2015—This study aimed to determine whether different levels of hypoxia affect physical performance during high-intensity resistance exercise or subsequent cardiovascular and perceptual responses. Twelve resistance-trained young men (age, 25.3 ± 4.3 years; height, 179.0 ± 4.5 cm; body mass, 83.4 ± 9.1 kg) were tested for 1 repetition maximum (1RM) in the back squat and deadlift. Following this, participants completed 3 separate randomized trials of 5 × 5 repetitions at 80% 1RM, with 3 minutes rest between sets, in normoxia (NORM; fraction of inspired oxygen [FIO2] = 0.21), moderate-level hypoxia (FIO2 = 0.16), or high-level hypoxia (FIO2 = 0.13) by a portable hypoxic unit. Peak and mean force and power variables were monitored during exercise. Arterial oxygen saturation (SpO2), heart rate (HR), and rating of perceived exertion (RPE) were assessed immediately following each set. No differences in force or power variables were evident between conditions. Similar trends were evident in these variables across each set and across the exercise session in each condition. SpO2 was lower in hypoxic conditions than in NORM, whereas HR was higher following sets performed in hypoxia. There were no differences between conditions in RPE. These results indicate that a hypoxic stimulus during high-intensity resistance exercise does not alter physical performance during repetitions and sets or affect how strenuous exercise is perceived to be. This novel training strategy can be used without adversely affecting the physical training dose experienced and may provide benefits over the equivalent training in NORM.

The validity of endurance running performance on the Curve 3TM non-motorised treadmill

Abstract This study aimed to test the validity of a non-motorised treadmill (NMT) for the measurement of self-paced overground endurance running performance. Ten male runners performed randomised 5-km running time trials on a NMT and an outdoor athletics track. A range of physiological and perceptual responses was measured, and foot strike was classified subjectively. Performance time was strongly correlated (r = 0.82, ICC = 0.86) between running modes, despite running time being significantly longer on the NMT (1264 ± 124 s vs. 1536 ± 130 s for overground and NMT, respectively; P < 0.001). End blood lactate concentration and rating of perceived exertion were significantly higher on the NMT compared to overground. Integrated electromyography was significantly lower on the NMT for three muscles (P < 0.05), and mean stride rate was also significantly lower on the NMT (P = 0.04). Cardiorespiratory responses of heart rate, oxygen uptake and expired air volume demonstrated strong correlations (r = 0.68–0.96, ICC = 0.75–0.97) and no statistical differences (P > 0.05). Runners were consistently slower on the NMT, and as such it should not be used to measure performance over a specific distance. However, the strong correlations suggest that superior overground performance was reflected in relative terms on the NMT, and therefore, it is a valid tool for the assessment of endurance running performance in the laboratory.