JOURNAL OF SPORTS SCIENCE & MEDICINE
SELF-REPORTED DIETARY INTAKE FOLLOWING ENDURANCE, RESISTANCE AND CONCURRENT ENDURANCE AND RESISTANCE TRAINING
Brandon S. Shaw1, Ina Shaw2 and Gregory A. Brown3
1Tshwane University of Technology and 2Vaal University of Technology, Republic of South Africa
3University of Nebraska at Kearney, Nebraska, USA
© Journal of Sports Science and Medicine (2008) 7, 255 - 259
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|With regards to obesity-related disease the impact of exercise
training on health depends on the ability of exercise to promote a negative
energy balance. Exercise's effect on promoting a negative energy balance
is more likely to occur if exercise can induce a favourable dietary intake
such as a reduced relative fat content in the diet. As such, the aim of
this study was to evaluate and compare the effectiveness of aerobic training,
weight training and concurrent aerobic and weight training on self-reported
dietary intake. The effects of 16 weeks of aerobic (n = 12), weight (n =
13) and concurrent aerobic and weight training (n = 13) on self-reported
dietary intakes were compared in previously sedentary males using the computer-based
Dietary Manager® software programme. Only the concurrent aerobic and weight
training group showed significant (p < 0.05) reductions in total kilocalories,
carbohydrates, proteins and fats consumed while the aerobic training group
showed significant reductions in fat intake at the completion of the experimental
period (before: 91.0 ± 42.1g versus after: 77.1 ± 62.1g). However, no changes
were observed in self-reported dietary intake in the weight training or
non-exercising control groups. It is concluded that concurrent aerobic and
weight training is the most effective mode of exercise at promoting a favourable
improvement in self-reported dietary intake in the short term. This finding
provides support for efforts to promote increases in overall physical activity
in an attempt to modify the patterns of dietary intake.
Key words: Kilocalories, carbohydrate, diet, exercise, fat, protein.
|Exercise has frequently been a method used to promote good health.
One expected favourable effect of exercise training is a positive change
in dietary habits and nutritional status (Ambler et al., 1998;
Tremblay and Almeras, 1995).
Epidemiological studies have also focused on the interaction between exercise
and diet (Sallis, 1993;
Sclicker et al., 1994).
This is due to the ever-increasing incidences of diseases such as hypertension,
dyslipidemia, diabetes mellitus, obesity and cardiovascular disease resulting
from sedentary lifestyles (Sallis, 1993;
Sclicker et al., 1994)
and an increased over-consumption of energy-dense food (whether fat, protein
or carbohydrate) (Olivares et al., 2004).
Since exercise is known to affect carbohydrate, protein and fat metabolism
and/or stores, it is hypothesized that exercise also affects their dietary
intake via its metabolic effects (Tremblay and Almeras, 1995).
This hypothesis is supported by Saris, 1989
who stated that there is a strong association between daily energy expenditure
and dietary intake.
With regards to exercise, Verger et al., 1992 found that energy intake increased from carbohydrate (but not fat or protein) following a two-hour vigorous exercise bout using college-aged males and females. However, a later study of Verger et al., 1994 found that protein (but not carbohydrate or fat) intake increased above rest in a male-only sample following two hours of various athletic activities. These contradictory findings might be explained by Ambler et al., 1998 when they found that fitness is associated with increased energy intakes in males but not females while females consumed greater quantities of fat and lesser quantities of carbohydrate. Additionally, a study by Titchenal, 1988 found that while athletes increase energy intake in response to an increased exercise volume, obese subjects did not alter their energy intake. Further confounding the effect of exercise on dietary intake, Costill et al., 1988 found that an increase in swimming training volume over a 10-day period resulted in their sample of athletes failing to increase their dietary carbohydrate intake leading to decreases in muscle glycogen levels and concomitant fatigue. This may be explained by a study by Janssen et al., 1989 who found that carbohydrate intakes increased by 3% to 4% in novice marathon runners but not in champion marathon runners. In this regard, champion athletes may increase energy intake through other dietary sources other than carbohydrates (de Wijn et al., 1979). This is confirmed more recently by Burke et al., 2003 when these researchers found that the dietary behaviour of 167 male and female Australian Olympic athletes following training was sub-optimal with regards to their dietary intake of carbohydrates, fats and proteins. Despite an increasing number of epidemiologic studies being conducted on the effect of aerobic exercise modalities and/or aerobic fitness, relatively few studies have been forthcoming on whether resistance training or a combination of aerobic and resistance training may affect energy intake through dietary sources. As such, the aim of the study was to evaluate and compare the effectiveness of aerobic training, weight training and concurrent aerobic and weight training on self-reported dietary intake.
were recruited from the Gauteng region in Johannesburg South Africa. A
total of 50 subjects took part in the 16-week study (Table
1). The study was approved by
the Rand Afrikaans University, Department of Human Movement Studies' Research
Committee and informed consent was obtained from each subject. The subjects
included were all males (mean age: 25 years and six months). The subjects
were screened and only those who were previously sedentary, free of preexisting
disease and not on any prescribed diet or supplement which could have
altered their dietary intake or energy expenditure were allowed to enter
the study. To account for the effect of exercise training on dietary intake,
the subjects had to complete a self-reported dietary intake form specifying
the type and quantity of food and fluids consumed over seven days before
and after the experimental period. Portion sizes were illustrated with
the aid of measuring cups, glasses, bowls and food items. The records
were reviewed in detail with each subject upon completion to ensure completeness.
The dietary records were analyzed for total kilocalories consumed, carbohydrates,
proteins and fats. The Dietary Manager® computer-based software
programme (Dietary Manager, Program Management, South Africa) was used
to analyze the data. The body mass of the subjects was measured to the
nearest 0.1 kilogramme on a calibrated medical scale (Mettler DT Digitol,
Mettler-Toledo AG, Ch-8606 GreiFensee, Switzerland) wearing only running
shorts. Percentage body fat was assessed using the seven-skinfold method
of Jackson and Pollock, 1978
which has a correlation of 0.915 when compared to hydrostatic weighing
to estimate body density. The standard error of estimate was 0.008 expressed
in body density and a standard error of estimate of 3.5 when expressed
in % BF using the equation of Siri, 1961
and standard errors of their formulae ranged from 3.6% to 3.8%.
The three exercising groups and the non-exercising control group
were found to be homogeneous at the start of the study regarding their
mean self-reported dietary intakes for total kilocalories (p = 0.686),
carbohydrates (p = 0.627), proteins (p = 0.729) and fats (p = 0.517).
At the end of the 16-week experimental period, the mean kilocalorie, carbohydrate
and protein intakes for the AER remained unchanged despite the finding
of a significant decrease the dietary intake of fat (91.0 ± 42.1 grammes
(g) at baseline versus 77.1 ± 62.1g at post-test). In the WEI, no significant
alterations were found in the measured dietary variables. However, following
16 weeks of concurrent aerobic and weight training, the WEI+AER was found
to have had significant (p < 0.05) decreases in total kilocalories
(2228 ± 598 kilocalories versus 1711 ± 675 kilocalories), carbohydrates
(236.4 ± 107.2g versus 185.5 ± 86.0g), proteins (103.5 ± 38.2g versus
80.2 ± 33.0g) and fats (91.9 ± 27.6g versus 67.9 ± 26.2g). As expected,
the CONT were found to have had no significant (p < 0.05) decreases
in their total kilocalories, carbohydrates, proteins and fats consumed.
ccording to the findings of the present study, engaging in concurrent
aerobic and weight training appears to result in a decreased consumption
of the usual self-reported dietary intakes regarding total kilocalories
consumed and from carbohydrates, proteins and fats in the short term.
Aerobic training resulted in a decreased self-reported dietary intake
of fats only, and weight training alone did not result in any change in
self-reported dietary macronutrient intake in the short term. This finding
is of interest because frequently the reduction in body mass associated
with exercise is less than is expected due to compensation for the increased
energy expenditure during exercise by either eating more food or having
less spontaneous physical activity throughout the day (Donnelly and Smith,
When combining this study's finding of a decreased self-reported dietary
consumption following concurrent aerobic and weight training with the
findings of a decreased %BF, the present data therefore suggests that
the most favourable technique for stimulating a negative energy balance
that might lead to reduced body mass is a combination of aerobic and resistance
|Concurrent aerobic and weight training is the most effective mode of exercise at promoting a favourable improvement in self-reported dietary intake in the short term. As such, efforts should be increased to promote increases in overall physical activity in an attempt to modify the patterns of dietary intake.|
authors are grateful to the Rand Afrikaans University, Johannesburg, South
Africa for the use of the Centre for Sport Science and Biokinetics and the
Vaal University of Technology for its statistical support.
Brandon S. SHAW
Employment: Lecturer - Tshwane University of Technology.
Research interests: Sports nutrition, Food preference and macronutrient intake in the obese and non-obese, metabolic diseases.
Employment: Lecturer - Vaal University of Technology.
Research interests: Diet and the aetiology of non-communicable diseases, Exercise and weight control, obesity.
Gregory A. BROWN
Employment: Associate Professor - University of Nebraska at Kearney.
Degree: PhD Health and Human Performance.
Research interests: Obesity, endocrinology of obesity and hunger, exercise and appetite regulation.