A selection of interesting studies

[Turk]

I keep finding loads of bodybuilding relevant studies that I always find of particular interest just for knowledge building that some of you may also find interesting.

Please don't take these as gospel truths, OuchThatHurts had a very good thread on using a pinch of salt when reading studies and they may not be entirely applicable to yourself or others, but are a good read or eye opener none the less.

If anyone else finds something they would like to share, please do add it in! Please try to use a little formatting however, as cut and pasted studies are hard to read if your not used to them. I've included the abstracts, as it's not always possible to access the full copy.

Enjoy and i hope we can all learn something!

If you find something in particular interesting, do say, and I can have a looksee at what else I can investigate in relation to it.

 

[Turk]

Creatine supplementation and cognitive performance in elderly individuals.

McMorris, T., Mielcarz, G., Harris, R.C., Swain, J.P., & Howard, A. (2007)

The purpose of this study was to examine the effect of creatine supplementation on the cognitive performance of elderly people. Participants were divided into two groups, which were tested on random number generation, forward and backward number and spatial recall, and long-term memory tasks to establish a baseline level. Group 1 (n = 15) were given 5 g four times a day of placebo for 1 week, followed by the same dosage of creatine for the second week. Group 2 (n = 17) were given placebo both weeks. Participants were retested at the end of each week. Results showed a significant effect of creatine supplementation on all tasks except backward number recall. It was concluded that creatine supplementation aids cognition in the elderly.

 

[Turk]

Effects of physical exercise on hand steadiness.

Simon, J., Richard, D., & Charles, E. (1965)

64 Ss performed a subminiature steadiness task which involved keeping a wire positioned in a circular hole so as not to contact the edge of the hole. The task was viewed through a stereoscopic microscope with a magnification of 40X. After initial scores were obtained, 1/2 the Ss performed a weight-lifting exercise while the remaining Ss rested. The immediate effect of exercise was a significant performance decrement as measured by both time in contact and number of contacts. A retest 24 hours later showed significant impairment due to exercise still evident in the time in contact score. In view of these results, surgeons might find it advisable to refrain from strenuous exercise for as long as 24 hours prior to microsurgery.

 

[Turk]

The effects of anabolic-androgenic steroid and thermogenic/ergogenic drug use on mood in powerlifters and bodybuilders.

Sanjuan, P.M. (2007)

Use of anabolic-androgenic steroids (AAS) has been associated with changes in mood, particularly increased anger, but also anxiety, mania, depression, confusion, vigor, and positive mood. Reports suggest a possible withdrawal syndrome occurring following AAS discontinuation. However, research has failed to account for other substances commonly used concurrently with AAS, especially thermogenic/ergogenic drugs (TEDs)-stimulants research has shown to be associated with the same mood effects attributed to AAS.

An Internet survey with 130 male bodybuilders/weightlifters aged 19-57, asked them to report current mood and use of AAS and TEDs, in order to determine effects of AAS and TEDs on mood and also whether those who had recently discontinued AAS reported withdrawal. Mood was measured with the Profile of Mood States---Brief, Self-Report Manic Inventory, Spielberger State/Trait Anger Expression Inventory---Revised, and Positive Automatic Thoughts Questionnaire. Because sample size was insufficient to detect small effects, effect sizes were reported. There were small effects where those using AAS (within 2 weeks) reported less mania (ES = .015), vigor (ES = .025, p = .021), and anger (ES = .013) than those not using AAS. There were small effects where those using TEDs (within 24 hours) reported greater mania (ES = .018), anxiety (ES = .023, p = .019), depression (ES = .011), vigor (ES = .017), and confusion (ES = .016) than those not using TEDs. Those who had discontinued use of AAS 2 wks--2 mos ago reported less mania (ES = .032), anxiety (ES = .026), fatigue (ES = .020), and total mood disorder (ES = .014), as well as greater vigor (ES = .032), anger feelings (ES = .043), verbal anger (ES = .043), physical anger (ES =.014), and total anger (ES = .033) than others.

This supported the theory that some mood effects associated with AAS may be caused by TEDs instead. There was no support for negative mood effects of AAS. There was no evidence that either TEDs or AAS contributed to increased anger, but there was evidence that AAS discontinuation may result in increased anger, although no evidence for a depressive withdrawal syndrome was found.

 

[Turk]

Effect of L-carnitine and/or L-acetyl-carnitine in nutrition treatment for male infertility: a systematic review.

Zhou, X., Liu, F., & Zhai, S. (2007)

The aim of this systematic review was to quantify the efficacy of L-carnitine (LC) and/or L-acetyl-carnitine (LAC) in nutrition treatment for male infertility according to present clinical evidence. Biomedical databases were searched to collect related clinical trials and nine relevant randomized controlled trials (RCTs) were included. The quality of the RCTs was assessed based on their performance in randomization, blinding, and allocation concealment. The meta-analysis compared LC and /or LAC therapy to placebo treatment found significant improvement in pregnancy rate (OR = 4.10, 95% CI (2.08, 8.08), p< 0.0001), total sperm motility (WMD = 7.43, 95% CI (1.72, 13.14), p = 0.04, forward sperm motility (WMD = 11.83, 95% CI (0.49, 23.16), p = 0.04) and atypical sperm cell (WMD = -5.72, 95% CI (-7.89, -3.56), p< 0.00001). However, no significant difference was found in the sperm concentration (WMD = 5.69, 95% CI (-4.47, 15.84), p = 0.27) and semen volume (WMD = 0.28, 95% CI (-0.02, 0.58), p = 0.07).

In conclusion, the administration of LC and/or LAC may be effective in improving pregnancy rate and sperm kinetic features in patients affected by male infertility. However, the exact efficacy of carnitines on male infertility needs to be confirmed by further investigations.

 

[Turk]

New insights concerning the role of carnitine in the regulation of fuel metabolism in skeletal muscle.

Stephens, F.B., Constantin-Teodosiu, D., & Greenhaff, P.L. (2007)

In skeletal muscle, carnitine plays an essential role in the translocation of long-chain fatty-acids into the mitochondrial matrix for subsequent beta-oxidation, and in the regulation of the mitochondrial acetyl-CoA/CoASH ratio. Interest in these vital metabolic roles of carnitine in skeletal muscle appears to have waned over the past 25 years. However, recent research has shed new light on the importance of carnitine as a regulator of muscle fuel selection.

It has been established that muscle free carnitine availability may be limiting to fat oxidation during high intensity submaximal exercise. Furthermore, increasing muscle total carnitine content in resting healthy humans (via insulin-mediated stimulation of muscle carnitine transport) reduces muscle glycolysis, increases glycogen storage and is accompanied by an apparent increase in fat oxidation. By increasing muscle pyruvate dehydrogenase complex (PDC) activity and acetylcarnitine content at rest, it has also been established that PDC flux and acetyl group availability limits aerobic ATP re-synthesis at the onset of exercise (the acetyl group deficit).

Thus, carnitine plays a vital role in the regulation of muscle fuel metabolism. The demonstration that its availability can be readily manipulated in humans, and impacts on physiological function, will result in renewed business and scientific interest in this compound.

 

[Turk]

Muscle dysmorphia in male weightlifters: a case-control study.

Olivardia, R., Pope, H.G. Jr., & Hudson, J.I. (2000)

OBJECTIVE: Muscle dysmorphia is a form of body dysmorphic disorder in which individuals develop a pathological preoccupation with their muscularity.

METHOD: The authors interviewed 24 men with muscle dysmorphia and 30 normal comparison weightlifters, recruited from gymnasiums in the Boston area, using a battery of demographic, psychiatric, and physical measures.

RESULTS: The men with muscle dysmorphia differed significantly from the normal comparison weightlifters on numerous measures, including body dissatisfaction, eating attitudes, prevalence of anabolic steroid use, and lifetime prevalence of DSM-IV mood, anxiety, and eating disorders. The men with muscle dysmorphia frequently described shame, embarrassment, and impairment of social and occupational functioning in association with their condition. By contrast, normal weightlifters displayed little pathology. Indeed, in an a posteriori analysis, the normal weightlifters proved closely comparable to a group of male college students recruited as a normal comparison group in an earlier study.

CONCLUSIONS: Muscle dysmorphia appears to be a valid diagnostic entity, possibly related to a larger group of disorders, and is associated with striking and stereotypical features. Men with muscle dysmorphia differ sharply from normal weightlifters, most of whom display little psychopathology. Further research is necessary to characterize the nosology and potential treatment of this syndrome.

 

[Turk]

Muscle dysmorphia: a critical review of the proposed criteria.

Chung, B. (2001)

While body-image related disorders such as anorexia nervosa have focused on thinness, only recently have clinical criteria for a disorder that centers around muscularity--muscle dysmorphia--been proposed. An individual affected by muscle dysmorphia is overly concerned with his or her degree of muscularity.This preoccupation is manifested in the individual's behavior (excessive weight lifting, excessive attention to diet, social impairment).This article examines the historical aspects and proposed criteria for muscle dysmorphia and contrasts them with those of anorexia nervosa.

While the authors of the proposed criteria have suggested that muscle dysmorphia be classified as a subcategory of body dysmorphic disorder, both the historical and clinical aspects of this syndrome are more consistent with its classification as an obsessive-compulsive disorder.

 

[Turk]

Toothbrushing with vegetable oil: a clinical and laboratorial analysis

Aguiar, A.A., & Saliba, N.A. (2004)

The dentifrices currently available in the marketplace contain many anticariogenic substances, fluoride and abrasives aimed to better clean the dental surface, remove dental plaque, improve salivary flow and its buffer capacity and reduce colonies of bacteria such as S. mutans, the causative agent of dental caries. The objective of this study was to evaluate the possibility of adequately removing dental plaque using an experimental almond oil dentifrice (Titoil) with no abrasives or antiplaque agents.

This study was carried out with 80 volunteers, all of them 18-year-old recruits from the military training school of Araçatuba -- SP. Saliva sampling and dental plaque disclosing were undertaken both before and after 28 days of toothbrushing with a low abrasive dentifrice (Group 1: 40 volunteers) or with Titoil (Group 2: 40 volunteers). Statistical analysis of the results revealed that the experimental dentifrice (Titoil) did not interfere with salivary flow and reduced dental plaque more than the low abrasive dentifrice, improved the salivary buffer capacity and decreased salivary S. mutans (Caritest-SM) as much as regular dentifrices. It was concluded that if the dental industry replaces abrasive by vegetable oil in dentifrices, these will be more effective in maintaining oral health and will cause less dental abrasion.

 

[Turk]

Almonds and almond oil have similar effects on plasma lipids and LDL oxidation in healthy men and women.

Hyson, D.A., Schneeman, B.O., & Davis, P.A. (2002)

Epidemiologic and clinical studies have shown that nut consumption is associated with favorable plasma lipid profiles and reduced cardiovascular risk. These effects may result from their high monounsaturated fat (MUFA) content but nuts contain constituents other than fatty acids that might be cardioprotective. We conducted a study to compare the effects of whole-almond vs. almond oil consumption on plasma lipids and LDL oxidation in healthy men and women. Using a randomized crossover trial design, 22 normolipemic men and women replaced half of their habitual fat (approximately 14% of approximately 29% energy) with either whole almonds (WA) or almond oil (AO) for 6-wk periods. Compliance was ascertained by monitoring dietary intake via biweekly 5-d food records, return of empty almond product packages and weekly meetings with a registered dietitian.

Fat replacement with either WA and AO resulted in a 54% increase in percentage of energy as MUFA with declines in both saturated fat and cholesterol intake and no significant changes in total energy, total or polyunsaturated fat intake. The effects of WA and AO on plasma lipids did not differ compared with baseline; plasma triglyceride, total and LDL cholesterol significantly decreased, 14, 4 and 6% respectively, whereas HDL cholesterol increased 6%. Neither treatment affected in vitro LDL oxidizability.

We conclude that WA and AO do not differ in their beneficial effects on the plasma lipid variables measured and that this suggests that the favorable effect of almonds is mediated by components in the oil fraction of these nuts.

 

[meanjoebean]

I enjoy reading these very much, thanks for putting time into posting them. I hope they'll be more in the future.

 

[Turk]

I enjoy reading these very much, thanks for putting time into posting them. I hope they'll be more in the future.

Thanks! There probably will be more, i've discovered they're very good at being productive procrastinators

 

[Turk]

Risk assessment for the amino acids taurine, l-glutamine and l-arginine.

Shao, A., & Hathcock, J.N. (2008)

Taurine, glutamine and arginine are examples of amino acids which have become increasingly popular as ingredients in dietary supplements and functional foods and beverages. Animal and human clinical research suggests that oral supplementation of these amino acids provides additional health and/or performance benefits beyond those observed from normal intake of dietary protein.

The increased consumer awareness and use of these amino acids as ingredients in dietary supplements and functional foods warrant a comprehensive review of their safety through quantitative risk assessment, and identification of a potential safe upper level of intake. The absence of a systematic pattern of adverse effects in humans in response to orally administered taurine (Tau), l-glutamine (Gln) and l-arginine (Arg) precluded the selection of a no observed adverse effect level (NOAEL) or lowest observed adverse effect level (LOAEL). Therefore, by definition, the usual approach to risk assessment for identification of a tolerable upper level of intake (UL) could not be used. Instead, the newer method described as the Observed Safe Level (OSL) or Highest Observed Intake (HOI) was utilized.

The OSL risk assessments indicate that based on the available published human clinical trial data, the evidence for the absence of adverse effects is strong for Tau at supplemental intakes up to 3g/d, Gln at intakes up to 14g/d and Arg at intakes up to 20g/d, and these levels are identified as the respective OSLs for normal healthy adults. Although much higher levels of each of these amino acids have been tested without adverse effects and may be safe, the data for intakes above these levels are not sufficient for a confident conclusion of long-term safety, and therefore these values are not selected as the OSLs.

 

[Turk]

A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study.

Frestedt, J.L., Zenk, J.L., Kuskowski, M.A., Ward, L.S., & Bastian, E.D. (2008)

BACKGROUND: This study evaluated a specialized whey fraction (Prolibratrade mark, high in leucine, bioactive peptides and milk calcium) for use as a dietary supplement to enhance weight loss.

METHODS: This was a randomized, double-blind, parallel-arm, 12-week study. Caloric intake was reduced 500 calories per day. Subjects consumed Prolibra or an isocaloric ready-to-mix beverage 20 minutes before breakfast and 20 minutes before dinner. Body fat and lean muscle tissue were measured by dual-energy x-ray absorptiometry (DEXA). Body weight and anthropometric measurements were recorded every 4 weeks. Blood samples were taken at the beginning and end of the study. Statistical analyses were performed on all subjects that completed (completer analysis) and all subjects that lost at least 2.25 kg of body weight (responder analysis). Within group significance was determined at P < 0.05 using a two-tailed paired t-test and between group significance was determined using one way analysis of covariance with baseline data as a covariate.

RESULTS: Both groups lost a significant amount of weight and the Prolibra group tended to lose more weight than the control group; however the amount of weight loss was not significantly different between groups after 12 weeks. Prolibra subjects lost significantly more body fat compared to control subjects for both the completer (2.81 vs. 1.62 kg P = 0.03) and responder (3.63 vs. 2.11 kg, P = 0.01) groups. Prolibra subjects lost significantly less lean muscle mass in the responder group (1.07 vs. 2.41 kg, P = 0.02). The ratio of fat to lean loss (kg fat lost/kg lean lost) was much larger for Prolibra subjects for both completer (3.75 vs. 1.05) and responder (3.39 vs. 0.88) groups.

CONCLUSION: Subjects in both the control and treatment group lost a significant amount of weight with a 500 calorie reduced diet. Subjects taking Prolibra lost significantly more body fat and showed a greater preservation of lean muscle compared to subjects consuming the control beverage. Because subjects taking Prolibra lost 6.1% of their body fat mass, and because a 5% reduction of body fat mass has been shown to reduce the risk of obesity related disease, the results have practical significance.

 

[Turk]

Caffeine and insulin sensitivity.

Acheson, K.J. (2005)

A number of reports have observed that acute caffeine ingestion decreases glucose tolerance and insulin sensitivity, and have raised the question whether its increased consumption throughout the world in the form of coffee and cola beverages might be of public health concern in the development of type 2 diabetes. Although some epidemiologic studies have found strong associations between coffee intake and detrimental lifestyle factors that favor obesity and diabetes, it is interesting that in spite of this, they have demonstrated that increased coffee consumption is associated with a decreased risk of developing type 2 diabetes.

When lifestyle confounders are taken into account, individuals consuming >/=6 cups coffee per day have at least 50% less risk of developing type 2 diabetes than those consuming </=2 cups per day. Although it is perhaps premature to recommend increased coffee or caffeine intake to prevent the development of type 2 diabetes, there is little or no evidence to warrant the recommendation that it should not be a part of a normal healthy diet.

 

[Turk]

Milk as an effective post-exercise rehydration drink.

Shirreffs, S.M., Watson, P., & Maughan, R.J. (2007)

The effectiveness of low-fat milk, alone and with an additional 20 mmol/l NaCl, at restoring fluid balance after exercise-induced hypohydration was compared to a sports drink and water. After losing 1.8 (sd 0.1) % of their body mass during intermittent exercise in a warm environment, eleven subjects consumed a drink volume equivalent to 150 % of their sweat loss. Urine samples were collected before and for 5 h after exercise to assess fluid balance. Urine excretion over the recovery period did not change during the milk trials whereas there was a marked increase in output between 1 and 2 h after drinking water and the sports drink. Cumulative urine output was less after the milk drinks were consumed (611 (sd 207) and 550 (sd 141) ml for milk and milk with added sodium, respectively, compared to 1184 (sd 321) and 1205 (sd 142) ml for the water and sports drink; P < 0.001).

Subjects remained in net positive fluid balance or euhydrated throughout the recovery period after drinking the milk drinks but returned to net negative fluid balance 1 h after drinking the other drinks. The results of the present study suggest that milk can be an effective post-exercise rehydration drink and can be considered for use after exercise by everyone except those individuals who have lactose intolerance.

 

[Turk]

Psychological Effects of Music Tempi during Exercise.

Karageorghis, C., Jones, L., & Stuart, D.P. (2007)

The purpose of this study was to investigate the effects of music tempi on music preference, intrinsic motivation, and flow during long-duration exercise ( approximately 26 min). Subjects (n = 29) selected the music of a single artist then walked at 70 % of maximum heart rate reserve (maxHRR) on a treadmill under three experimental conditions (medium tempi, fast tempi, and mixed tempi) and a no-music control.

A music preference item, the Intrinsic Motivation Inventory, and Flow State Scale-2 were completed after each trial. Data were analyzed using a mixed-model (Gender x Condition) ANOVA and MANOVA. The Gender x Condition interaction was nonsignificant in both analyses (p > 0.05). Contrary to expectations, higher preference scores were recorded for medium tempi than for mixed tempi (means: 7.8 +/- 1.3 vs. 7.1 +/- 1.1). The medium tempi music also yielded the highest levels of intrinsic motivation (p < 0.001).

Pairwise comparisons showed that interest-enjoyment was higher for medium tempi when compared to mixed tempi, 95 % CI = 1.80 - 8.48, p = 0.001, and that each of the music preference experimental conditions yielded higher scores than the no-music control. Also, pressure-tension was lower for medium tempi compared to fast tempi, 95 % CI = - 3.44 - 0.19, p = 0.022, and for both medium and mixed tempi compared to control (95 % CI = - 5.33 - 2.89, p = 0.000; 95 % CI = - 4.24 - 0.64, p = 0.004). A main effect was found for global flow (p = 0.000) with the highest mean score evident in the medium tempi condition (14.6 +/- 1.5).

Follow-up comparisons indicated that the medium tempi condition yielded higher flow scores than the control, 95 % CI = 1.25 - 3.60, p = 0.000, as did fast tempi, 95 % CI = 0.89 - 3.14, p = 0.000, and mixed tempi, 95 % CI = 1.36 - 3.76, p = 0.000. It was concluded that a medium tempi music program was the most appropriate for an exercise intensity of 70 % maxHRR.

 

[Turk]

Experimental comparison of the psychological benefits of aerobic exercise, humor, and music.

Szabo, A., Ainsworth, S.E., & Danks, P.K. (2005)

The effects of aerobic exercise, humor, and music on the state anxiety and affect of healthy women were investigated by using a 'within participants' design. Twenty women were tested four times at weekly intervals. They were exposed to four 20-minute treatments in a counterbalanced order: 1) stationary cycling at 50% of their maximal heart rate reserve, 2) watching a humorous video, 3) listening to new-age music, and 4) sitting quietly. Participants' state anxiety and affect were measured 5-minutes before and 5-minutes after each treatment.

Statistically significant decreases in state anxiety were observed in all four conditions. Negative affect also decreased in all but the sitting quietly (control) condition. The calculated effects sizes, reflecting the meaningfulness of the intervention-induced changes, were highest in response to humor session, followed by music and exercise. It is concluded, therefore, that the immediate psychological benefits of humor and music are comparable to the psychological benefits of a bout of aerobic exercise.

 

[Turk]

Darwinism in the Gym.

Pope, C.C., & O'Sullivan, M. (2003)

This study examined the ecology of "free gym" as it occurred in both school lunch hour and after-school community settings. In an effort to understand how urban youth experience sport, an ethnography using multiple methods was conducted to ascertain how urban youth shape their own cultures according to the social forces operating within the gymnasium. A period of sustained observation revealed a student-imposed hierarchy that was dominated by skilled male African American basketball players.

Status was gained through what occurred within the free-gym ecology. Students often had to learn the system by "serving time" before they could join a desired level of the hierarchy. While a few students thrived in this environment, most merely survived or were marginalized. Such a setting has implications for how physical education and school culture is subjected to wider societal influences. The presence of socially chronic situations such as free gym require a pedagogy that is more democratic and more enriching, thereby moving from the real toward the ideal.

 

[Turk]

Weight-loss diet that includes consumption of medium-chain triacylglycerol oil leads to a greater rate of weight and fat mass loss than does olive oil.

St-Onge, M.P., Bosarge, A. (2008)

BACKGROUND: Clinical studies have shown that consumption of medium-chain triacylglycerols (MCTs) leads to greater energy expenditure than does consumption of long-chain triacylglycerols. Such studies suggest that MCT consumption may be useful for weight management.

OBJECTIVE: We aimed to determine whether consumption of MCT oil improves body weight and fat loss compared with olive oil when consumed as part of a weight-loss program.

DESIGN: Forty-nine overweight men and women, aged 19-50 y, consumed either 18-24 g/d of MCT oil or olive oil as part of a weight-loss program for 16 wk. Subjects received weekly group weight-loss counseling. Body weight and waist circumference were measured weekly. Adipose tissue distribution was assessed at baseline and at the endpoint by use of dual-energy X-ray absorptiometry and computed tomography.

RESULTS: Thirty-one subjects completed the study (body mass index: 29.8 +/- 0.4, in kg/m(2)). MCT oil consumption resulted in lower endpoint body weight than did olive oil (-1.67 +/- 0.67 kg, unadjusted P = 0.013). There was a trend toward greater loss of fat mass (P = 0.071) and trunk fat mass (P = 0.10) with MCT consumption than with olive oil. Endpoint trunk fat mass, total fat mass, and intraabdominal adipose tissue were all lower with MCT consumption than with olive oil consumption (all unadjusted P values < 0.05).

CONCLUSIONS: Consumption of MCT oil as part of a weight-loss plan improves weight loss compared with olive oil and can thus be successfully included in a weight-loss diet. Small changes in the quality of fat intake can therefore be useful to enhance weight loss.