Hierarchical framework to improve individualised exercise prescription in adults: a critical review.

Physical activity (PA) guidelines for the general population are designed to mitigate the rise of chronic and debilitating diseases brought by inactivity and sedentariness. Although essential, they are insufficient as rates of cardiovascular, pulmonary, renal, metabolic and other devastating and life-long diseases remain on the rise. This systemic failure supports the need for an improved exercise prescription approach that targets the individual. Significant interindividual variability of cardiorespiratory fitness (CRF) responses to exercise are partly explained by biological and methodological factors, and the modulation of exercise volume and intensity seem to be key in improving prescription guidelines. The use of physiological thresholds, such as lactate, ventilation, as well as critical power, have demonstrated excellent results to improve CRF in those struggling to respond to the current homogenous prescription of exercise. However, assessing physiological thresholds requires laboratory resources and expertise and is incompatible for a general population approach. A case must be made that balances the effectiveness of an exercise programme to improve CRF and accessibility of resources. A population-wide approach of exercise prescription guidelines should include free and accessible self-assessed threshold tools, such as rate of perceived exertion, where the homeostatic perturbation induced by exercise reflects physiological thresholds. The present critical review outlines factors for individuals exercise prescription and proposes a new theoretical hierarchal framework to help shape PA guidelines based on accessibility and effectiveness as part of a personalised exercise prescription that targets the individual.

Effects of 12-Week Low or Moderate Dietary Acid Intake on Acid-Base Status and Kidney Function at Rest and during Submaximal Cycling.

Prolonged effects of dietary acid intake on acid-base status and kidney function have not yet been studied in an intervention study in healthy subjects. Dietary acid load can be estimated by calculating the potential renal acid load (PRAL) of foods. Effects of low-PRAL and moderate-PRAL diets on acid-base status and kidney function were investigated during a 12-week exercise training period. Healthy, 20-50-year-old men (n = 21) and women (n = 25) participated in the study and were randomly divided into low-PRAL and moderate-PRAL groups. Before (PRE), mid-phase (MID) and after the intervention (POST), the subjects participated in measurement sessions, where a 12-h urine sample and fasting blood samples were collected, and a submaximal cycle ergometer test was performed. Net acid excretion was significantly lower after 12 weeks of the low-PRAL diet as compared to the moderate-PRAL diet, both in men and women. In low-PRAL females, capillary pH and bicarbonate were significantly higher at 75% of VO2max at POST as compared to PRE. Glomerular filtration rate decreased over the study period in moderate-PRAL men and women. The results of the present study suggest that an acidogenic diet and regularly training together may increase the acidic load of the body and start to impair the kidney function in recreationally active subjects.

Neuromuscular Adaptations to Combined Strength and Endurance Training: Order and Time-of-Day.

The present study examined the effects of 24 weeks of morning vs. evening same-session combined strength (S) and endurance (E) training on neuromuscular and endurance performance. Fifty-one men were assigned to the morning (m) or evening (e) training group, where S preceded E or vice versa (SEm, ESm, SEe and ESe), or to the control group. Isometric force, voluntary activation, EMG and peak wattage during the maximal cycling test were measured. Training time did not significantly affect the adaptations. Therefore, data are presented for SEm+e (SEm+SEe) and ESm+e (ESm+ESe). In the morning, no order specific gains were observed in neuromuscular performance. In the evening, the changes in isometric force (SEm+e 15.9±16.7%, p=0.001; ESm+e 4.1±12.2%, p=0.615) and EMG (SEm+e 38.3±31.7%, p=0.001; ESm+e 14.67±36.44%, p=0.486) were larger (p=0.014) in SEm+e than in ESm+e and in voluntary activation larger (p=0.026) in SEm+e compared to controls. Peak wattage increased in the morning (SEm+e 15.9±9.2%, ESm+e 22.0±7.0%; p<0.001) and evening (SEm+e 16.3±7.2%, ESm+e 21.0±9.0%; p<0.001) but were larger (p<0.05) in ESm+e. The current training program led to greater neuromuscular adaptations when SE-training was performed in the evening, whereas the ES-training provided more optimal conditions for endurance performance adaptations both in the morning and evening.

Fitness, body composition and blood lipids following 3 concurrent strength and endurance training modes.

This study investigated changes in physical fitness, body composition, and blood lipid profile following 24 weeks of 3 volume-equated concurrent strength and endurance training protocols. Physically active, healthy male and female participants (aged 18-40 years) performed strength and endurance sessions on different days (DD; men, n = 21; women, n = 18) or in the same session with endurance preceding strength (ES; men, n = 16; women, n = 15) or vice versa (SE; men, n = 18; women, n = 14). The training volume was matched in all groups. Maximal leg press strength (1-repetition maximum (1RM)) and endurance performance (maximal oxygen consumption during cycling), body composition (dual-energy X-ray absorptiometry), and blood lipids were measured. 1RM and maximal oxygen consumption increased in all groups in men (12%-17%, p < 0.001; and 7%-18%, p < 0.05-0.001, respectively) and women (13%-21%, p < 0.01-0.001; and 10%-25%, p < 0.01-0.001, respectively). Maximal oxygen consumption increased more in DD vs. ES and SE both in men (p = 0.003-0.008) and women (p = 0.008-0.009). Total body lean mass increased in all groups (3%-5%, p < 0.01-0.001). Only DD led to decreased total body fat (men, -14% ± 15%, p < 0.001; women, -13% ± 14%, p = 0.009) and abdominal-region fat (men, -18% ± 14%, p = 0.003; women, -17% ± 15%, p = 0.003). Changes in blood lipids were correlated with changes in abdominal-region fat in the entire group (r = 0.283, p = 0.005) and in DD (r = 0.550, p = 0.001). In conclusion, all modes resulted in increased physical fitness and lean mass, while only DD led to decreases in fat mass. Same-session SE and ES combined training is effective in improving physical fitness while volume-equated, but more frequent DD training may be more suitable for optimizing body composition and may be possibly useful in early prevention of cardiovascular and metabolic diseases.

The effects of a roundtrip trans-American jet travel on physiological stress, neuromuscular performance, and recovery.

The purpose was to examine the effects of a round trip trans-American jet travel on performance, hormonal alterations, and recovery. Ten matched pairs of recreationally trained men were randomized to either a compression group (COMP) (n = 10; age: 23.1 ± 2.4 yr; height: 174.8 ± 5.3 cm; body mass: 84.9 ± 10.16 kg; body fat: 15.3 ± 6.0%) or control group (CONT) (n = 9; age: 23.2 ± 2.3 yr; height: 177.5 ± 6.3 cm; weight: 84.3 ± 8.99 kg; body fat: 15.1 ± 6.4%). Subjects flew directly from Hartford, CT to Los Angeles, CA 1 day before a simulated sport competition (SSC) designed to create muscle damage and returned the next morning on an overnight flight back home. Both groups demonstrated jet lag symptoms and associated decreases in sleep quality at all time points. Melatonin significantly (P < 0.05) increased over the first 2 days and then remained constant until after the SSC. Epinephrine, testosterone, and cortisol values significantly increased above resting values before and after the SSC with norepinephrine increases only after the SSC. Physical performances significantly decreased from control values on each day for the CONT group with COMP group exhibiting no significant declines. Muscle damage markers were significantly elevated following the SSC with the COMP group having significantly lower values while maintaining neuromuscular performance measures that were not different from baseline testing. Trans-American jet travel has a significant impact on parameters related to jet lag, sleep quality, hormonal responses, muscle tissue damage markers, and physical performance with an attenuation observed with extended wear compression garments.

Acute Endocrine and Force Responses and Long-Term Adaptations to Same-Session Combined Strength and Endurance Training in Women.

This study examined acute hormone and force responses and strength and endurance performance and muscle hypertrophy before and after 24 weeks of same-session combined strength and endurance training in previously untrained women. Subjects were assigned 1 of 2 training orders: endurance preceding strength (E + S, n = 15) or vice versa (S + E, n = 14). Acute force and hormone responses to a combined loading (continuous cycling and a leg press protocol in the assigned order) were measured. Additionally, leg press 1 repetition maximum (1RM), maximal workload during cycling (Wmax), and muscle cross-sectional area (CSA) were assessed. Loading-induced decreases in force were significant (p < 0.01-0.001) before (E + S = 20 ± 11%, S + E = 18 ± 5%) and after (E + S = 24 ± 6%, S + E = 22 ± 8%) training. Recovery was completed within 24 hours in both groups. The acute growth hormone (GH) response was significantly (p < 0.001) higher after S + E than E + S at both weeks 0 and 24. Testosterone was significantly (p < 0.001) elevated only after the S + E loading at week 24 but was not significantly different from E + S. Both groups significantly (p < 0.001) improved 1RM (E + S = 13 ± 12%, S + E = 16 ± 10%), Wmax (E + S = 21 ± 10%, S + E = 16 ± 12%), and CSA (E + S = 15 ± 10%, S + E = 11 ± 8%). This study showed that the acute GH response to combined endurance and strength loadings was significantly larger in S + E compared with E + S both before and after 24 weeks of same-session combined training. Strength and endurance performance and CSA increased to similar extents in both groups during 24 weeks despite differences in the kinetics of GH. Previously untrained women can improve performance and increase muscle CSA using either exercise order.

Acute neuromuscular and endocrine responses and recovery to single-session combined endurance and strength loadings: "order effect" in untrained young men.

The purpose of this study was to investigate acute neuromuscular and endocrine responses and recovery to a single session of combined endurance and strength loading using 2 loading orders. Forty-two men were demographically matched to perform a single session of combined endurance + strength (E + S) or strength + endurance (S + E) loading. The strength loading was conducted on a leg press and included sets of power, maximal strength, and hypertrophic loads with an overall duration of 30 minutes. The endurance loading was conducted on a bike ergometer and performed by continuous cycling over 30 minutes at 65% of subject's individual maximal watts. Both loading conditions led to significant acute reductions in maximal force production (E + S: -27%, p < 0.001; S + E: -22%, p < 0.001), rapid force produced in 500 milliseconds (E + S: -26%, p < 0.001; S + E: -18%, p < 0.001), and countermovement jump height (E + S: -15%, p < 0.001; S + E: -12%, p < 0.001), whereas no significant differences between the 2 loadings were observed. Maximal and explosive force production recovered after 48 hours after both loading conditions. Whereas no significant acute responses were found in concentrations of serum testosterone (T) and thyroid-stimulating hormone in the 2 loading conditions, concentrations of T were significantly reduced in E + S during recovery at 24 hours (-13%, p < 0.05) and 48 hours (-11%, p = 0.068), but not in S + E, and concentrations of thyroid-stimulating hormone significantly reduced after both loading conditions (24 hours: E + S, -32%, p < 0.001; S + E, -25%, p < 0.01; 48 hours: E + S, -25%, p < 0.001; S + E, -18%, p < 0.01). The loading conditions in this study showed that neuromuscular performance recovered already within 2 days, whereas endocrine function, observed particularly by decreased concentrations in serum T after the E + S loading order, remained altered still after 48 hours of recovery. These results emphasize the different needs for recovery after 2 loading orders.