Aging under pressure:The roles of reactive oxygen and nitrogen species (rons) production and aging skeletal muscle in endothelial function and hypertension—from biological processes to potential interventions

The proportion of adults living with hypertension increases significantly with advancing age. It is therefore important to consider how health and vitality can be maintained by the aging population until end of life. A primary risk factor for the progression of cardiovascular diseases (CVD) is hypertension, so exploring the factors and processes central to this burden of disease is essential for healthy aging. A loss of skeletal muscle quantity and quality is characteristic in normal aging, with a reduction of vasodilatory capacity caused by endothelial dysfunction, and subsequent increase in peripheral resistance and risk for hypertension. Reactive Oxygen and Nitrogen Species (RONS) encompass the reactive derivatives of NO and superoxide, which are continuously generated in contracting skeletal muscle and are essential mediators for cellular metabolism. They act together as intra and intercellular messengers, gene expression regulators, and induce programmed cell death. In excessive amounts RONS can inflict damage to endothelial and skeletal muscle cells, alter signaling pathways or prematurely promote stress responses and potentially speed up the aging process. The age-related increase in RONS by skeletal muscle and endothelial mitochondria leads to impaired production of NO, resulting in vascular changes and endothelial dysfunction. Changes in vascular morphology is an early occurrence in the etiology of CVDs and, while this is also a normal characteristic of aging, whether it is a cause or a consequence of aging in hypertension remains unclear. This review serves to focus on the roles and mechanisms of biological processes central to hypertension and CVD, with a specific focus on the effects of aging muscle and RONS production, as well as the influence of established and more novel interventions to mediate the increasing risk for hypertension and CVD and improve health outcomes as we age

Sex Differences in Autonomic Cardiac Control and Oxygen Saturation Response to Short-Term Normobaric Hypoxia and Following Recovery: Effect of Aerobic Fitness

Introduction: The main aims of this study were to investigate autonomic nervous system (ANS) and arterial oxygen saturation (SpO2) responses to simulated altitude in males and females, and to determine the association between maximal oxygen uptake (VO2max) and these responses.Materials and Methods: Heart rate variability (HRV) and SpO2 were monitored in a resting supine position during Preliminary (6 min normoxia), Hypoxia (10 min, fraction of inspired oxygen (FiO2) of 9.6%, simulated altitude ~6,200 m) and Recovery (6 min normoxia) phases in 28 males (age 23.7 ± 1.7 years, normoxic VO2max 59.0 ± 7.8 ml.kg−1.min−1, body mass index (BMI) 24.2 ± 2.1 kg.m−2) and 30 females (age 23.8 ± 1.8 years, VO2max 45.1 ± 8.7 ml.kg−1.min−1, BMI 21.8 ± 3.0 kg.m−2). Spectral analysis of HRV quantified the ANS activity by means of low frequency (LF, 0.05–0.15 Hz) and high frequency (HF, 0.15–0.50 Hz) power, transformed by natural logarithm (Ln). Time domain analysis incorporated the square root of the mean of the squares of the successive differences (rMSSD).Results: There were no significant differences in SpO2 level during hypoxia between the males (71.9 ± 7.5%) and females (70.8 ± 7.1%). Vagally-related HRV variables (Ln HF and Ln rMSSD) exhibited no significant differences between sexes across each phase. However, while the sexes demonstrated similar Ln LF/HF values during the Preliminary phase, the males (0.5 ± 1.3) had a relatively higher (p = 0.001) sympathetic activity compared to females (−0.6 ± 1.4) during the Hypoxia phase. Oxygen desaturation during resting hypoxia was significantly correlated with VO2max in males (r = −0.45, p = 0.017) but not in females (r = 0.01, p = 0.952) and difference between regression lines were significant (p = 0.024).Conclusions: Despite similar oxygen desaturation levels, males exhibited a relatively higher sympathetic responses to hypoxia exposure compared with females. In addition, the SpO2 response to resting hypoxia exposure was related to maximal aerobic capacity in males but not females

The indirect impact of road freight transport - case study: N3 Johannesburg to Durban road freight corridor

South Africa's unique spatial challenges require more corridor transport relative to the size of the economy than most countries in the world. The overall aim of this investigation is to determine the estimated cost of the indirect impacts of road freight on the N3 corridor between Johannesburg and Durban. This corridor, approximately 600 kilometres in length, forms the link between the country's industrial hub (Johannesburg) and its key Port (Durban). The following research questions are posed: • What is the status quo of freight transport in a global, South African and Johannesburg to Durban Freight Corridor context? • What are the future growth forecasts for freight on the Johannesburg to Durban corridor? • What is the significance of freight transport in South Africa? • Does the reported total cost of road freight transport take into account a holistic approach when determining the costs? • How are direct and indirect impacts of road freight transport defined, and how do they differ? • What are the direct and indirect impacts of road freight transport? • What method can be used to assess the total indirect costs of all associated impacts? • What are the estimated costs of the indirect impacts of road freight transport on the Johannesburg to Durban Freight Corridor? • What are possible mitigation measures for the indirect impacts of road freight transport? • What will the estimated costs of the indirect impacts of road freight transport on the Johannesburg to Durban Freight Corridor be in over a 30-year horizon, when considering future projections and possible mitigation measures? • What are the alternative modes to road freight transport on the Johannesburg to Durban corridor

Effects of Short-Term High versus Continuous Moderate Intensity Training on Insulin Resistance in Overweight and Obese Adults: A Randomized Controlled Trial

International Journal of Exercise Science 12(3): 1057-1069, 2019. In long-term exercise training studies ( \u3e 6 weeks), improvements in insulin resistance (IR) are amplified by decreased body fat and/or increased cardio-respiratory fitness. This presents a challenge in studying the independent effects of exercise training. Our study purpose was to determine the effects of short-term continuous moderate intensity training (CMIT) and high intensity interval training (HIIT) on IR in overweight/obese adults. Participants were stratified into insulin sensitive (IS) and IR groups, and randomized into non-exercise control (CNT), CMIT and HIIT sub-groups that underwent baseline and post testing. Exercise sessions were 18-24 minutes for 10 consecutive days. The CMIT sub-group continuously cycled at 60-70% of peak oxygen consumption (V̇O2peak) while the HIIT sub-group performed 60s of cycling at 90-100% V̇O2peak interspersed with 30 seconds of rest. Ninety-five participants (mean age and BMI 23.9 + 3.9 years and 32.1 + 5.0 kg/m2) were enrolled into the study. Of these, 63% were IS and 37% had IR. CMIT or HIIT did not result in statistically significant improvements in IR. However, the reduction (32.4%) in IR observed with HIIT may be of clinical relevance. Cohen’s (d) effect size (ES) for HIIT on IR was large (ES: d = -0.9; 95% CI: -1.7, -0.1) while that of CMIT was unclear (ES: d = -0.2; 95% CI: -1.0, 0.6). In the current study, CMIT or HIIT did not result in statistically significant improvements in insulin resistance. Future large-scale studies to clarify and confirm our findings are warranted

The effects of a multi-ingredient supplement on markers of muscle damage and inflammation following downhill running in females

BACKGROUND: The effects of a multi-ingredient performance supplement (MIPS) on markers of inflammation and muscle damage, perceived soreness and lower limb performance are unknown in endurance-trained female athletes. The purpose of this study was to determine the impact of MIPS (NO-Shotgun®) pre-loaded 4 weeks prior to a single-bout of downhill running (DHR) on hsC-Reactive Protein (hsCRP), interleukin (IL)-6, creatine kinase (CK), muscle soreness, lower limb circumferences and performance. METHOD: Trained female runners (n = 8; 29 ± 5.9 years) (VO(2max): ≥ 50 ml(-1).kg(-1).min(-1), midfollicular phase (7-11 days post-menses) were randomly assigned in a double-blind manner into two groups: MIPS (n = 4) ingested one serving of NO Shotgun daily for 28 days prior to DHR and 30 min prior to all post-testing visits; Control (CON) (n = 4) consumed an isocaloric maltodextrin placebo in an identical manner to MIPS. hsCRP, IL-6, CK, perceived soreness, limb circumferences, and performance measures (flexibility, squat jump peak power) were tested on 5 occasions; immediately before (PRE), immediately post-DHR, 24, 48 and 72 h post-DHR. RESULTS: There were main effects of time for CK (p = 0.05), pain pressure threshold (right tibialis anterior (p = 0.010), right biceps femoris (p = 0.01), and left iliotibial band (ITB) (p = 0.05) across all time points), and maximum squat jump power (p = 0.04). Compared with 24 h post-DHR, maximum squat jump power was significantly lower at 48 h post-DHR (p = 0.05). Lower body perceived soreness was significantly increased at 24 h (p = 0.02) and baseline to 48 h (p = 0.02) post DHR. IL-6 peaked immediately post-DHR (p = 0.03) and hsCRP peaked at 24 h post-DHR (p = 0.06). Calculation of effect sizes indicated a moderate attenuation of hsCRP in MIPS at 72 h post-DHR. CONCLUSIONS: Consumption of MIPS for 4 weeks prior to a single bout of DHR attenuated inflammation three days post, but did not affect perceived soreness and muscle damage markers in endurance trained female runners following a single bout of DHR

The use of laser doppler fluxmetry in the pre-operative assessment of amputation wound healing in the dysvascular patient.

Masters Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF

Lifestyle modification in the management of insulin resistance states in overweight/obesity: the role of exercise training

Physical inactivity is a major contributor to overweight/obesity and associated disorders including cardiovascular diseases (CVDs), diabetes, and insulin resistance (IR). Intensive lifestyle modification (ILM) is recommended as first-line treatment for obese individuals at risk for IR. Exercise is considered to be a critical component of ILM. This narrative review discusses the role of exercise in the management of IR in overweight/obesity. PubMed and Google Scholar were searched for articles published between January 1990 and January 2019 that examined mechanisms behind the effects of exercise on IR states associated with overweight/obesity. Studies examining and/comparing effects of exercise mode, volume and/intensity on IR were also retrieved. Medical Subject Headings (MeSH) used were ‘metabolic diseases’ OR ‘chronic diseases’ AND ‘exercise’ and their related terms. Text words used in conjunction with the MeSH terms were ‘aerobic training/exercise’ OR ‘resistance training/exercise’ OR ‘high intensity interval training/exercise’, OR ‘low volume training/exercise’. Reference lists of retrieved articles were also searched for appropriate studies. Aerobic exercise training (AET) and resistance exercise training (RET) appear to produce comparable effects on obesityinduced IR states. RET, however, appears to be associated with greater improvements in glucose disposal in skeletal muscle, which is usually the primary site for IR. This is partly attributed to greater increases in key proteins involved in the insulin signalling pathway including protein content of glucose transporter 4 (GLUT-4) following RET. A study on individuals with impaired glucose tolerance (IGT) showed that RET improved glucose disposal by 23%, primarily due to a 27% increase in non-oxidative glucose metabolism, suggesting that RET may delay the manifestation of diabetes in patients with IGT. Furthermore, studies reviewed here show that components of exercise including the mode, volume and intensity of exercise training are an integral element in exercise prescription and must be recommended in accordance with the desired outcome

Somatic, endurance performance and heart rate variability profiles of professional soccer players grouped according to age

This cross-sectional study compared somatic, endurance performance determinants and heart rate variability (HRV) profiles of professional soccer players divided into different age groups: GI (17–19.9 years; n = 23), GII (20–24.9 years; n = 45), GIII (25–29.9 years; n = 30), and GIV (30–39 years; n = 26). Players underwent somatic and HRV assessment and maximal exercise testing. HRV was analyzed by spectral analysis of HRV, and high (HF) and low (LF) frequency power was transformed by a natural logarithm (Ln). Players in GIV (83 ± 7 kg) were heavier (p < 0.05) compared to both GI (73 ± 6 kg), and GII (78 ± 6 kg). Significantly lower maximal oxygen uptake (VO2max, ml•kg-1•min-1) was observed for GIV (56.6 ± 3.8) compared to GI (59.6 ± 3.9), GII (59.4 ± 4.2) and GIV (59.7 ± 4.1). All agegroups, except for GII, demonstrated comparable relative maximal power output (Pmax). For supine HRV, significantly lower Ln HF (ms2) was identified in both GIII (7.1 ± 0.8) and GIV (6.9 ± 1.0) compared to GI (7.9 ± 0.6) and GII (7.7 ± 0.9). In conclusion, soccer players aged >25 years showed negligible differences in Pmax unlike the age group differences demonstrated in VO2max. A shift towards relative sympathetic dominance, particularly due to reduced vagal activity, was apparent after approximately 8 years of competing at the professional level