Physical activity and obesity among Year 7 children in Kent, U.K: Gender, social background, reasons for being active and implications for school health promotion

Aims This study explored to what extent level of physical activity (PA) and obesity are associated with gender and socio-economic status (SES) among Year 7 children. Furthermore, we wanted to gain insight into the most common reasons for being physically active in these children. Methods 678 children were recruited from five secondary schools in Kent, U.K (Boys=397, Girls=281). The mean age was 11.34. To gather information on pattern and psychosocial variables of PA, children were asked to fill in the questionnaire which was adapted from the Health Behaviour in School-Aged Children (HBSC) survey. Anthropometric measures of children’s weight, height and skinfold thickness were obtained. Considering PA pattern, adiposity level and psychosocial variables, differences and correlations were explored in Gender and SES groups. Results This study confirmed the difference in both levels and types of PA between boys and girls. There were no significant differences in PA patterns among SES groups, apart from the membership of sports club. Significant correlation was found between PA and encouragement from both parents and friends. The difference in gender groups in importance for the following was found; building up strength, taking part in competitions and win, improving my physical skills and pleasing their family, while in SES groups; taking part in competition and win and pleasing my family. Correlations between PA and the following were found to be significant; becoming healthy, building up strength, enjoying myself and have fun, being part of a team, making new friends. Conclusions Gender has strong associations with PA patterns; levels and types of PA, as well as importance of reasons for PA. This gender difference should be considered in the school settings. Encouragement from parents and friends is also a good facilitator. Especially, friends are important. Becoming healthy, enjoying themselves and having fun and improving physical skills were found to be important for children. These aspects should be generated when it comes to promotion of PA among school children

Hypermobility and sports injury

Objective To determine whether there is an association between hypermobility and sports injury. Methods A quantitative observational approach using a cross-sectional survey was adopted. Individuals were identified as hypermobile or not. All participants were asked to complete two questionnaires: one asking demographic information and the other injury-specific. Fisher’s exact test was used for statistical analysis. Results 114 individuals participated in the study, 62 women and 52 men. 26% of the participants were hypermobile. There was no significant association between hypermobility and sports injury (p=0.66). There was a significant increase in joint and ligament sprain among the non-hypermobile (NH) group covering all sports (p=0.03). Joint dislocation was found exclusively among hypermobile individuals. The duration of injury in hypermobile individuals was higher than NH. The use of oral painkillers or anti-inflammatories in the semiprofessional group was greater than the general population. Conclusion Hypermobility is relatively common among individuals, and there is a lot of anecdotal evidence associating it with increased rates of injuries. This project finds that NH individuals are more likely to sustain a ligament or joint sprain in sports. This is due to increased joint laxity and flexibility preventing injury. There were important limitations to this study which will be addressed in further work. These include assessing for pauciarticular hypermobility and focusing on one sport to investigate its association with sports injury in those who are hypermobile or not. It would also be important to focus on one specific joint, assessing its flexibility and association with injur

The effects of isometric exercise training on femoral and brachial artery dimension and blood flow in middle-aged men.

Introduction Previous isometric training studies reporting reductions in resting blood pressure have not explored whether there are concomitant changes in resting artery dimensions and blood flow. Furthermore, the influence of isometric training intensity on these adaptations has not been investigated. Therefore, the purpose of this study was to explore whether training-induced reductions in resting blood pressure are associated with concomitant changes in the vasculature of the trained and untrained limbs and to establish if these adaptations were intensity dependent. Methods Subjects undertook an 8 week training programme consisting of 4x2 min bilateral-leg isometric contractions 3 x per week (Wiles et al., 2010). Two groups exercised at intensities equivalent to 70% (n=10) or 85% (n=10) of their peak heart rate (%HRpeak; as established in a prior incremental test), and a third group acted as controls (n=10). Resting systolic (SBP), mean arterial (MAP) and diastolic (DBP) blood pressure was measured at baseline and post-training. Artery diameter and mean blood flow (brachial and femoral) were also measured at rest using Doppler ultrasound. Analysis of variance was used to determine whether post-training measures were significantly different to baseline. Also, baseline values were used as a covariate to account for initial resting blood pressure values. Results There were significant reductions in resting SBP (-10.8±7.9 mmHg) and MAP (-4.7±6.8 mmHg) in the 85%T group post-training and concomitant significant increases in resting femoral mean artery diameter (FMAD; 1.0±0.4 mm) and femoral mean blood velocity (FMBV; 0.68±0.83 cm/s), which resulted in increased femoral artery blood flow (FABF; 82.06±31.92 ml/min). There were no significant changes in brachial artery measures after training. Furthermore, there were no significant changes in any resting measure in the 70%T or control group. Discussion This study shows that the reductions in resting SBP and MAP observed after isometric training are associated with concomitant increases in resting artery dimensions and blood flow, but these changes were restricted to the trained limbs. This suggests that the vascular adaptations were localised. Furthermore, these adaptations seem to be training-intensity dependent, as they were not observed in the 70%T training group. These findings could be explained by reduced resting vascular tone, enhanced endothelium-dependent function or by vascular remodelling. The stimulus for such adaptations may arise from changes in availability/activity of nitric oxide as a result of sheer stresses during isometric exercise (McGowan et al. 2007). Exactly how these sheer stresses occur during isometric exercise and how they might be related to isometric training intensity would be deserving of future study. McGowan CL, Levy AS, McCartney N, MacDonald MJ. (2007). Clin. Sci. 112, 403-409. Wiles JD, Coleman DA, Swaine IL. (2010). Eur. J. Appl. Physiol. 108, 419-428

Responses to an isometric leg-exercise test predicts sex-specific training-induced reductions in resting blood pressure after isometric leg training

Isometric training, using either isometric handgrip (IHG) or isometric bilateral-leg (IBL) protocols, is an effective method of lowering resting systolic blood pressure (SBPrest). However, the reductions in SBPrest seen after training vary widely between individuals. Predicting likely training-induced reductions in SBPrest could make it possible to optimise the effects of the training in all participants. It is known that post-IHG training reductions in SBPrest can be predicted by SBP responses to a 2 minute IHG task in both hypertensive and older normotensives (Millar et al., 2009; Badrov et al., 2013). However, the predictability of such a test in younger individuals and when using a comparable IBL task, has not been established. Furthermore, it is not known whether these simple isometric tests can predict reductions in ambulatory SBP (mean 24-hour, SBPamb) as well as SBPrest. Therefore, the purpose of this study was to determine whether an IBL test can be used to predict training-induced reductions in SBPrest and SBPamb following 10 weeks of IBL training in young men and women.Resting and ambulatory BP (SBPrest and SBPamb) were measured prior to and following 10 weeks of IBL training using an isokinetic dynamometer (4, 2-minute contractions at 20% MVC with 2 minute rest periods, 3/week) in 20 normotensive individuals (10 men, age=21 ± 4 years; 10 women, age=23 ± 5 years). SBP responses to the IBL test (single 2-minute period of IBL exercise) was derived by calculating the difference between peak SBP and mean baseline SBPrest. Pearson’s product moment correlation coefficient was used to assess the relationship between the blood pressure responses to a short 2-minute IBL test and the magnitude of the reductions in SBPrest and SBPamb after IBL training.ResultsThere were significant reductions in men and women’s SBPrest (7.4±5.1mmHg, p=0.0001 & 5.7±4.1mmHg, p=0.001) and SBPamb (4.0±1.9mmHg, p=0.011 & 6.1±5.8mmHg, p=0.0001) following training. These changes in SBPrest were strongly correlated with pre-training SBP response to the IBL test in both men (r=-0.83, p=0.003, SEE=3.03) and women (r = -0.81, p=0.004, SEE=2.56). However, the magnitude of the reductions in SBPamb were not correlated with SBP response to the IBL test (men, r=-0.44, p=0.199, SEE=1.76; women, r=-0.23, p=0.517, SEE=6.01).These results support previous research which has identified that IBL training is an effective tool for lowering both resting and ambulatory BP. Furthermore, a simple isometric exercise test can be used as a tool to predict reductions in resting SBP, but not ambulatory SBP, after IBL training in both men and women. This test could be used to optimise the effects of this type of training in a wider range of participants, perhaps through modification of the training, to suit the anticipated effects in different individuals

Commentary on Aerobic versus isometric handgrip exercise in hypertension: a randomized controlled trial

We, members of the International Working Group on Isometric Exercise, read with great interest the article by Pagonas et al. on the comparative effects of aerobic and isometric handgrip exercise (IRT). However, we believe the finding, that aerobic exercise induces reductions in blood pressure (BP), whereas isometric exercise training (handgrip) does not, to be compromised for several reasons

The Effects of Training Involving Simultaneous Walking with Isometric Exercise on Resting Blood Pressure in Young Healthy Adults

Introduction In separate studies, walking and isometric training have been shown to reduce resting blood pressure. Combined aerobic and resistance training, where participants undertake one element of the training programme followed by the second has been seen to produce larger reductions in resting blood pressure (BP) compared to a single exercise protocol such as, walking (Calders et al. 2010). To date, no studies have investigated the effects of simultaneous, combined training on resting BP. Therefore, this study aims to determine the effect of 6-weeks simultaneous, combined isometric (handgrip) and walking training (HGW) on resting systolic (SBP) and diastolic blood pressure (DBP), compared to a walking training programme (WLK). Methods A total of 26 healthy sedentary participants (male, n = 16; female, n = 10; age 21.3±2yrs; mass 69.2±12.5kg; height 170.4±9cm) were randomly allocated, into three groups walking training (WLK; n=12), simultaneous walking and handgrip training (HGW; n=12) or controls. Resting SBP, DBP and mean arterial blood pressure (MAP) were measured at baseline and post-training. Analysis of covariance was used to determine if post-training measures were significantly different to baseline, using the baseline values as the covariate. Results The preliminary data show that, in the three groups, resting SBP was reduced after the 6-weeks, by -12.3, -6.7 and -0.4 mmHg, for HGW, WLK and CON groups respectively. DBP was reduced by -6.4, -3.3 and -0.2 mmHg and MAP by -3.3, -2.2 and -0.2 mmHg. Whilst all changes in the HGW and WLK groups were significant (P<0.05), there were no significant changes in any of the resting blood pressure measured in the control group. Discussion The results indicate that combining walking with simultaneous handgrip isometric exercise, caused greater reductions in resting SBP, DBP and MAP, than walking only. The magnitude of the changes in the HGW group are substantially greater than those observed in previous walking only studies (7.4-1.9 mmHg; Murphy et al. 2007) despite a considerably shorter training intervention. The reductions are also greater than many of the previous studies involving handgrip only training in normotensive participants (McGowan et al. 2007). These sizeable reductions in resting BP emphasise the antihypertensive potential of simultaneous combined exercise training especially since they are evident even in individuals whose BP is considered to be in the normal range. Calders P, Elmahgoub S, Roman de Mettelinge T, Vanderbroeck C, Dewandele I Rombaut L, Vandevelde A, Cambier D. (2011). Clin. Rhab. 25, 1097-1108. McGowan CL, Levy AS, McCartney N, MacDonald MJ. (2007). Clin. Sci. 112, 403-409. Murphy MH, Nevill AM, Murtagh EM, Holder RL. (2007). Preventive Med. 44, 377-385

Establishing Equivalent Training Intensities for Isometric Bilateral-Leg and Handgrip Exercise Using the Category Ratio Scale

Isometric handgrip (IHG) training is commonly undertaken at an exercise intensity of 30% of a subject’s maximum voluntary contraction (MVC) (McGowan et al., 2007). Matching this intensity with isometric bilateral-leg (IBL) exercise is difficult due to the different muscle mass involved. Comparative studies (Howden et al., 2002) have tended to use different exercise intensities without providing a strong rationale. Therefore, the purpose of this study was to use the Category Ratio Scale (CR-10) to establish equivalent exercise intensities for IHG and IBL, based on participant effort perception and to test the extent to which intensity can be matched, when using this method during training sessions. A total of 26 healthy participants (male, n = 18; female, n = 8) undertook two minutes of unilateral IHG to establish the mean CR-10 values. Then, performed IBL exercise at 15, 20 and 25%MVC. The IBL intensity at which CR-10 most-closely matched the values for IHG, was identified as 20%MVC. Subsequently, an IHG and IBL training session was used, to test the extent to which the intensities were matched, according to effort perception. Ten participants (male, n = 6; female, n = 4) undertook 4 x 2 minutes unilateral IHG (30%MVC) and IBL (20%MVC) training, with 2 minutes recovery between contractions with CR-10 measured at the end of each exercise bout. A one-way independent ANOVA was used to identify the IHG and IBL intensities that were most-closely matched. To determine whether CR-10 values were significantly different during the IHG and IBL training sessions, a two-way mixed-model ANOVA was used.The intensity at which CR-10 was most-closely matched between IHG and IBL was 20%MVC. There were significant differences in the CR-10 values between IHG contractions at 30%MVC and IBL at 25%MVC and 15%MVC (P > 0.05) but not at 20%MVC (P 0.05).These results suggest when performing IBL exercise, the intensity most closely matching the IHG intensity (30%MVC) is 20%MVC. Furthermore, it can be seen from the simulated training sessions that CR-10 does not significantly differ between the two intensities until the final 2-minute bout. Therefore, it may be advantageous when undertaking one-off IBL exercise or IBL training protocols with the purpose of comparing data to that from IHG, to use 20%MVC. However, when a 4 x 2 minute training protocol is used, it may be necessary to attenuate the intensity of the 4th bout of IBL

Reductions in resting blood pressure in young adults when isometric exercise is performed whilst walking

Aerobic and isometric training have been shown to reduce resting blood pressure, but simultaneous aerobic and isometric training have not been studied. The purpose of this study was to compare the changes in resting systolic (SBP), diastolic (DBP), and mean arterial blood pressure (MAP) after 6 weeks of either (i) simultaneous walking and isometric handgrip exercise (WHG), (ii) walking (WLK), (iii) isometric handgrip exercise (IHG), or control (CON). Forty-eight healthy sedentary participants (age 20.7 ± 1.7 yrs, mass 67.2 ± 10.2 kg, height 176.7 ± 1.2 cm, male , and female ) were randomly allocated, to one of four groups ( in each). Training was performed 4 × week−1 and involved either treadmill walking for 30 minutes (WLK), handgrip exercise 3 × 10 s at 20% MVC (IHG), or both performed simultaneously (WHG). Resting SBP, DBP, and MAP were recorded at rest, before and after the 6-week study period. Reductions in resting blood pressure were significantly greater in the simultaneous walking and handgrip group than any other group. These results show that simultaneous walking and handgrip training may have summative effects on reductions in resting blood pressure

The Mechanism Underlying the Hypotensive Effect of Isometric Handgrip Training: Is it Cardiac Output Mediated?

Isometric handgrip (IHG) training lowers blood pressure (BP) in normotensive individuals yet the mechanisms remain equivocal, and some evidence suggests that men and women respond differently to training. To date, non-sex specific mechanisms influencing total peripheral resistance, either in response to a single IHG bout or with training, have been a primary research focus, and the effects of acute and chronic IHG on cardiac output (Q) in either sex are under-explored. The purpose of the current study was two-fold: 1) to investigate the effects of IHG training (4, 2-minute sustained bilateral isometric contractions at 30% of maximal contraction, 1-minute rest between, 3X/week for 10 weeks) on resting Q, and 2) to examine the Q response to an IHG bout, and the effects of training on this response. Resting BP (Dinamap Carescape v100, Critikon) was measured after 10 minutes of seated rest in twenty-two normotensive participants (10 women; mean age= 24 ± 5.0 years). To assess Q, aortic root diameter (ARD; 3S-RS probe; Vivid I, GE Healthcare), velocity-timed integral (VTI; P2D probe; Vivid I), and HR (Dinamap) were measured pre- and post- an IHG bout. Both variables were re-assessed post-training. Reductions in resting systolic BP of a similar magnitude (p>0.05) were observed in both men (2.4 ± 6.2 mmHg) and women (2.9 ± 4.6 mmHg) following 10 weeks of training (p=0.04). This was accompanied by reductions in resting Q (p=0.007) in both men (6.6 ± 2.2 to 6.3 ± 1.8 L/min) and women (5.8 ± 0.7 to 5.1 ± 0.8 L/min) and reductions in HR (p=0.036), both of which were similar between sexes (all p>0.05). In both groups, no changes in Q were observed in response to an IHG bout, and this response was similar pre- and post- training (all p>0.05). In conclusion, resting Q is reduced with training, potentially implicating it as a mechanism of post-training BP reductions. The acute response to an IHG bout remains unchanged with training