Cardiovascular and metabolic demands of the kettlebell swing using a Tabata interval versus a traditional resistance protocol

International Journal of Exercise Science 7(3) : 179-185, 2014. Tabata (TAB) training, consisting of eight cycles of 20 seconds of maximal exercise followed by 10 seconds of rest, is time-efficient, with aerobic and anaerobic benefit. This study investigated the cardiovascular and metabolic demands of a TAB versus traditional (TRAD) resistance protocol with the kettlebell swing. Fourteen young (18-25y), non-obese (BMI 25.7±0.8 kg/m2) participants reported on three occasions. All testing incorporated measurements of HR, oxygen consumption, and blood lactate accumulation. Each participant completed Tabata kettlebell swings (male- 8kg, female- 4.5kg; 8 intervals; 20s maximal repetitions, 10s rest). On a subsequent visit (TRAD), the total swings from the TAB protocol were evenly divided into 4 sets, with 90s rest between sets. Outcome measures were compared using paired t-tests. The TAB was completed more quickly than the TRAD protocol (240.0±0.0 v. 521.5±3.3 sec, P\u3c0.01), at a higher perceived exertion (Borg RPE; 15.1±0.7 v. 11.7±0.9, P\u3c0.01). The TAB elicited a higher average VO2 value (33.1±1.5 v. 27.2±1.6 ml/kg/min, P\u3c0.01), percent of VO2peak achieved (71.0±0.3 v. 58.4±0.3%, P\u3c0.01), maximal HR (162.4±4.6 v. 145.6±4.8 bpm, P\u3c0.01), and post-exercise blood lactate concentration (6.4±1.1 v. 3.7±0.5 mmol/L, P\u3c0.01). Conclusion: The kettlebell swing demonstrated significantly greater cardiovascular and metabolic responses within a TAB vs. TRAD framework. Appropriate screening and risk stratification are advised before implementing kettlebell swings

Differential Response To Tabata Interval Versus Traditional Kettlebell Training Protocol

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Observation of Inter-arm Systolic Blood Pressure Difference During Exercise

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The importance of experimental time when assessing the effect of temperature on toxicity in poikilotherms

Temperature is an important factor affecting toxicity, determining chemical toxicokinetics and toxicodynamics in poikilothermic organisms. As also metabolic rates are affected by temperature, interactions between the emergence of toxic effects and time are very likely. The aim of this study was to investigate how temperature affected the toxicity of copper towards the nematode Caenorhabditis elegans when measured during short fixed timeframes compared to during full life-cycles. Copper toxicity was tested in two experiments at four or six temperatures in the range of 11 to 24°C, with copper concentrations spanning from one to 40 mg Cu/L agar, respectively. Reproduction and mortality were determined across the entire life-cycle, and the time to production of first egg and the population growth rate were calculated. The results showed that the 50% effect concentrations (EC50) of copper increased 1.5 to 2.5-fold with increasing temperature within the tested range, depending on endpoint. When calculating EC50 on reproduction after 24 or 96 hours, as is the typical setup for temperature/chemical interaction studies, results ranged from no temperature effect to effects much larger than for the full life cycle. Studies of temperature effects on toxicity must therefore be carefully designed in relation to the research question investigated

Earthworm distribution and abundance predicted by a process-based model

Earthworms are significant ecosystem engineers and are an important component of the diet of many vertebrates and invertebrates, so the ability to predict their distribution and abundance would have wide application in ecology, conservation and land management. Earthworm viability is known to be affected by the availability and quality of food resources, soil water conditions and temperature, but has not yet been modelled mechanistically to link effects on individuals to field population responses. Here we present a novel model capable of predicting the effects of land management and environmental conditions on the distribution and abundance of Aporrectodea caliginosa, the dominant earthworm species in agroecosystems. Our process-based approach uses individual based modelling (IBM), in which each individual has its own energy budget. Individual earthworm energy budgets follow established principles of physiological ecology and are parameterised for A. caliginosa from experimental measurements under optimal conditions. Under suboptimal conditions (e.g. food limitation, low soil temperatures and water contents) reproduction is prioritised over growth. Good model agreement to independent laboratory data on individual cocoon production and growth of body mass, under variable feeding and temperature conditions support our representation of A. caliginosa physiology through energy budgets. Our mechanistic model is able to accurately predict A. caliginosa distribution and abundance in spatially heterogeneous soil profiles representative of field study conditions. Essential here is the explicit modelling of earthworm behaviour in the soil profile. Local earthworm movement responds to a trade-off between food availability and soil water conditions, and this determines the spatiotemporal distribution of the population in the soil profile. Importantly, multiple environmental variables can be manipulated simultaneously in the model to explore earthworm population exposure and effects to combinations of stressors. Potential applications include prediction of the population-level effects of pesticides and changes in soil management e.g. conservation tillage and climate change

The Effect of Physical Activity on the Insulin Response to Frequent Meals

Long, uninterrupted bouts of sedentary behavior are thought to negatively influence insulin sensitivity, and may impact metabolic function regardless of adherence to general physical activity guidelines. The purpose of this study was to determine the combined effect of physical activity (1 h continuous exercise v. intermittent exercise throughout the day) and meal consumption on glucose excursions, insulin secretion, and appetite markers in obese individuals with prediabetes. Methods: Eleven healthy, obese subjects (\u3e30 kg/m2) with prediabetes underwent 3, 12 h study days including sedentary behavior (SED), exercise (EX; 1h morning exercise, 60-65% VO2 max), and physical activity (PA; 12 hourly, intensity-matched 5-minute bouts). Meals were provided every 2 h. Blood samples were taken every 10 min for 12 h. Baseline and area under the curve (AUC) for serum glucose, insulin, c-peptide, total PYY concentrations, and subjective appetite ratings; as well as insulin pulsatility were determined. Results: No significant differences in baseline glucose, insulin or c-peptide concentrations across study days were observed (P\u3e0.05). Glucose AUC (12 h and 2 h) were significantly different across study days, with AUC attenuated in the PA condition compared to the EX condition (P\u3c0.05). The 12 h incremental insulin AUC was reduced by PA compared to SED (173,985±3556.8 v. 227,352±4581.2 pmol/L*min for 12 h, respectively; P\u3c0.05). Similarly, a significant main effect of condition in the 2 h insulin AUC was found, with the PA condition being reduced compared to SED condition (P\u3c0.05), but no differences between the EX and SED conditions. A significant reduction in 2 h c-peptide AUC was demonstrated with EX and PA compared to the SED condition (P\u3c0.05). Deconvolution analysis of insulin secretion revealed no significant differences between experimental conditions. There were no significant differences in total PYY between experimental conditions, though subjective measures of hunger and satiety were reduced with continuous and intermittent exercise. Conclusions: Short bouts of physical activity throughout the day attenuate glucose excursions and improve insulin clearance compared to an exercise day with 1 h of morning exercise. Further, both continuous and intermittent exercise mechanisms that improve satiety in obese individuals are not related to changes in concentrations of PYY

Using the ‘Think Aloud’ Method to Inform Skinfold Instruction in Exercise Science

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Parental exposure to elevated pCO2 influences the reproductive success of copepods

Substantial variations are reported for egg production and hatching rates of copepods exposed to elevated carbon dioxide concentrations (pCO2). One possible explanation, as found in other marine taxa, is that prior parental exposure to elevated pCO2 (and/or decreased pH) affects reproductive performance. Previous studies have adopted two distinct approaches, either (1) expose male and female copepoda to the test pCO2/pH scenarios, or (2) solely expose egg-laying females to the tests. Although the former approach is more realistic, the majority of studies have used the latter approach. Here, we investigated the variation in egg production and hatching success of Acartia tonsa between these two experimental designs, across five different pCO2 concentrations (385–6000 µatm pCO2). In addition, to determine the effect of pCO2 on the hatching success with no prior parental exposure, eggs produced and fertilized under ambient conditions were also exposed to these pCO2 scenarios. Significant variations were found between experimental designs, with approach (1) resulting in higher impacts; here >20% difference was seen in hatching success between experiments at 1000 µatm pCO2 scenarios (2100 year scenario), and >85% at 6000 µatm pCO2. This study highlights the potential to misrepresent the reproductive response of a species to elevated pCO2 dependent on parental exposure