Effect Of Creatine Loading Research Articles

The Effects of Creatine Loading on Dynamic Balance, Mobility and Strength in Older Adults

Aging often attenuates balance and strength regardless of activity profile, thus resulting in an increased risk of falling. Older populations taking part in a resistance training program tend to minimize the loss of lean body mass, but still may suffer decrements. Creatine (Cr) supplementation has been studied extensively for almost 20 years and is a popular supplement of choice by athletes. Cr purportedly provides an enhancement of the phosphocreatine energy system allowing users to maintain a greater work intensity for an extended time. PURPOSE: To determine if acute Cr supplementation (20g of Cr/ day for 5 days) improves balance, mobility, and strength in older adult populations. METHODS: Ten subjects (age 64.4 ± 5.2 yr, ht. 168 ± 5.6 cm, body mass 76.3 ± 8.1 kg, ♀6) participated in familiarization trials conducted on the Biodex Balance SD [four conditions: normal stance w/ eyes open (NEO), N w/ eyes closed (NEC): and closed stance w/ eyes open (CEO), and C w/ eyes closed (CEC)], isokinetic knee extension (KE) and knee flexion (KF) peak torque (ft/lbs) and the Timed Up and Go Test (TUG) expressed in seconds. The battery of tests were conducted in the same sequence for each of the four assessments (pre control [PC], post control [PoC], pre Cr [PCr], and post Cr [PoCr]). Subjects were randomly assigned to 5 days of either 20 g of Cr or a matched placebo in a double blind protocol with a washout period of 14 days between treatments. Cr and placebo were indistinguishable in volume, taste, flavor, texture and color. RESULTS: Statistical analysis by ANOVA revealed NSD (p>.05) between treatments.Table: No title available.CONCLUSION: The acute use of Cr loading for individuals aged ≥60 was ineffective in altering muscular strength, balance or mobility for moderately active adults. It may require a longer period of loading or larger doses for creatine to be effective in older populations.

Effect of Creatine Loading on Oxygen Uptake during a 1-km Cycling Time Trial.

For the first time, we investigated the effects of altering cellular metabolic capacitance, via a 5-d creatine (Cr) loading protocol (20 g·d⁻¹), on oxygen uptake (VO2), accumulated oxygen deficit, muscle recruitment, and performance during a 1-km cycling time trial. In a double-blind, randomized, placebo-controlled design, 19 amateur cyclists were allocated to a Cr (n = 10, VO2peak = 56.0 ± 7.8 mL·kg⁻¹·min⁻¹) or placebo (n = 9, VO2peak = 56.0 ± 8.4 mL·kg⁻¹·min⁻¹) group, and performed a 1-km cycling time trial before and after the supplementation period. Body mass was significantly increased in the Cr group (P < 0.05), but not in the placebo group. Participants adopted an "all-out" pacing strategy in both groups. However, Cr loading reduced VO2 immediately after the beginning (12th to 23th seconds), and this was accompanied by a reduced aerobic and increased anaerobic contribution. The VO2 mean response time was slower (pre: 17.2 ± 5.6 s vs post: 19.9 ± 4.6 s), the total O2 uptake was reduced (pre: 4.64 ± 0.59 L vs post: 4.47 ± 0.53 L), and the oxygen deficit was increased (pre: 0.82 ± 0.27 L vs post: 0.98 ± 0.25 L) after Cr loading. No differences were observed in the placebo group for these variables. Plasma lactate and integrated electromyography were not altered in either group, nor was the time to complete the trial (Cr group: pre: 89.1 ± 6.7 s vs post 89.1 ± 6.2 s and placebo group: pre 85.9 ± 4.9 s vs post 87.0 ± 5.4 s). Cr loading slows the V˙O2 response and increases the anaerobic contribution during a 1-km cycling time trial.

The effects of creatine loading on oxygen uptake kinetics during heavy exercise

The kinetics of oxygen uptake during the rest to exercise transition are thought to be modulated by intracellular metabolic processes. Evidence suggests that increased phosphocreatine stores may impact the kinetics of VO2, namely, slowing kinetics due to the now increased ATP buffering capacity. Thus, the purpose of this study was to test the hypothesis that creatine loading would induce slowed VO2 kinetics during heavy leg cycling. Four (N=4) subjects completed three separate exercise bouts of heavy (supra‐lactate threshold) exercise both prior to and following a creatine loading regimen. VO2 was measured continuously at the mouth during exercise and recovery for each bout. During the on‐transition, the total amplitude was reduced following creatine loading (Atot: Control 1.22±0.26 vs Creatine 0.97±0.20 L/min, p = 0.03). The time constant during the off‐transition was also slower during the creatine trials (Tau: Control 36.4±9.3 vs Creatine 53.3±7.6 sec, p = 0.02). These findings suggest that an increase in the temporal buffering capacity of phosphocreatine reduces the on‐transient VO2 as well as, slowing the recovery kinetics of VO2.

The Effects of Creatine Loading and Gender on Anaerobic Running Capacity

The Effects of Creatine Loading and Gender on Anaerobic Running Capacity

The Effects of Creatine Loading and Gender on Anaerobic Running Capacity

Creatine (Cr) loading consists of short-term, high-dosage Cr supplementation and has been shown to increase intramuscular total Cr content. Increases in body weight (BW) have been shown to result from Cr loading, with differences by gender, and increased BW may impact weight-bearing exercise. The critical velocity (CV) test is used to quantify the relationship between total running distance and time to exhaustion. The CV test provides the variable, anaerobic running capacity (ARC), which is an estimate of the anaerobic energy reserves in muscle. The purpose of this study was to examine the effects of gender and Cr loading on ARC. Fifty moderately trained men and women volunteered to participate in this randomized, double-blinded, placebo (PL)-controlled, repeated-measures study. After a familiarization session, a 3-day testing procedure was conducted. A maximal oxygen consumption test VO(2)max) on a treadmill was performed on day 1 to establish the maximum velocity (Vmax) at VO(2)max and to record BW. Days 2 and 3 involved treadmill running at varying percentages of Vmax. Participants were randomly assigned to either the Cr or PL group and received 20 packets of the Cr supplement (1 packet = 5 g Cr citrate, 18 g dextrose) or 20 packets of the PL (1 packet = 18 g dextrose). After consuming 4 packets daily for 5 consecutive days, the 3-day testing procedure was repeated. The male Cr loading group exhibited a 23% higher (p = 0.003) ARC compared to the PL group. Nonsignificant BW increases were found for the Cr groups. These findings suggest that Cr loading may be an effective strategy for improving ARC in men, but not in women, and revealed only nonsignificant increases in BW. Creatine loading may be used before competition by athletes to provide improvements in high-intensity, short-duration activities.

Effects of Creatine Loading on Electromyographic Fatigue Threshold in Cycle Ergometry in College-Age Men

The purpose of this study was to examine the effects of 5 d of creatine (Cr) loading on the electromyographic fatigue threshold (EMG FT) in college-age men. Sixteen men (age 22.4 +/- 2.6 yr, height 177.4 +/- 6.8 cm, weight 79.5 +/- 10.6 kg; M +/- SD) participated in this double-blind study and were randomly placed into either placebo (Pl; 10 g of flavored fructose powder per packet; n = 8) or Cr (5 g dicreatine citrate plus 10 g of flavored fructose powder per packet; n = 8) loading groups. Each participant ingested 1 packet 4 times/d, totaling 20 g/d for 5 days (loading). Before and after loading, each participant performed a discontinuous cycle-ergometer test to determine his EMG FT, using bipolar surface electrodes placed on the vastus lateralis of the right thigh. Four 60-s work bouts (ranging from 200 to 400 W) were completed. Adequate rest was given between bouts to allow for the participants' heart rate (HR) to drop within 10 beats of their resting HR. The EMG amplitude was averaged over 5-s intervals for each 60-s work bout. Resulting slopes from each successive work bout were used to calculate EMG FT. A 2-way ANOVA, Group (Cr vs. Pl) x Time (pre vs. post), resulted in a nonsignificant (p > .05) interaction for supplement and time. In addition, a significant increase (p = .009) in weight was observed in the Cr group. These data suggest that there was a minimal influence of Cr loading on EMG FT for the participants in this study.

Effects of creatine loading on electromyographic fatigue threshold during cycle ergometry in college-aged women

The purpose of this study was to examine the effects of 5 days of Creatine (Cr) loading on the electromyographic fatigue threshold (EMGFT) in college-aged women. Fifteen healthy college-aged women (mean ± SD = 22.3 ± 1.7 yrs) volunteered to participate in this double-blind, placebo-controlled study and were randomly placed into either placebo (PL – 10 g of flavored dextrose powder; n = 8) or creatine (Cr – 5 g di-creatine citrate plus 10 g of flavored dextrose powder; n = 7; Creatine Edge, FSI Nutrition) loading groups. Each group ingested one packet 4 times per day (total of 20 g/day) for 5 days. Prior to and following supplementation, each subject performed a discontinuous incremental cycle ergometer test to determine their EMGFT value, using bipolar surface electrodes placed on the longitudinal axis of the right vastus lateralis. Subjects completed a total of four, 60 second work bouts (ranging from 100–350 W). The EMG amplitude was averaged over 10 second intervals and plotted over the 60 second work bout. The resulting slopes from each successive work bouts were used to calculate EMGFT. A two-way ANOVA (group [Cr vs. PL] × time [pre vs. post]) resulted in a significant (p = 0.031) interaction. Furthermore, a dependent samples t-test showed a 14.5% ± 3.5% increase in EMGFT from pre- to post-supplementation with Cr (p = 0.009), but no change for the PL treatment (-2.2 ± 5.8%; p = 0.732). In addition, a significant increase (1.0 ± 0.34 kg; p = 0.049) in weight (kg) was observed in the Cr group but no change for PL (-0.2 kg ± 0.2 kg). These findings suggest that 5 days of Cr loading in women may be an effective strategy for delaying the onset of neuromuscular fatigue during cycle ergometry.

The Effects of Creatine Loading on Thermoregulation and Intermittent Sprint Exercise Performance in a Hot Humid Environment

The purpose of this study was to determine the effects creatine (Cr) loading may have on thermoregulatory responses during intermittent sprint exercise in a hot/humid environment. Ten physically active, heat-acclimatized men performed 2 familiarization sessions of an exercise test consisting of a 30-minute low-intensity warm-up followed by 6 x 10 second maximal sprints on a cycle ergometer in the heat (35 degrees C, 60% relative humidity). Subjects then participated in 2 different weeks of supplementation. The first week, subjects ingested 5 g of a placebo (P, maltodextrin) in 4 flavored drinks (20 g total) per day for 6 days and were retested on day 7. The second week was similar to the first except a similar dose (4 x 5 g/day) of creatine monohydrate (Cr) replaced maltodextrin in the flavored drinks. Six days of Cr supplementation produced a significant increase in body weight (+1.30 +/- 0.63 kg), whereas the P did not (+0.11 +/- 0.52 kg). Compared to preexercise measures, the exercise test in the heat produced a significant increase in core temperature, a loss of body water determined by body weight change during exercise, and a relative change in plasma volume (%PVC); however, these were not significantly different between P and Cr. Sprint performance was enhanced by Cr loading. Peak power and mean power were significantly higher during the intermittent sprint exercise test following 6 days of Cr supplementation. It appears that ingestion of Cr for 6 days does not produce any different thermoregulatory responses to intermittent sprint exercise and may augment sprint exercise performance in the heat.

Effects of creatine loading and prolonged creatine supplementation on body composition, fuel selection, sprint and endurance performance in humans

Most research on creatine has focused on short-term creatine loading and its effect on high-intensity performance capacity. Some studies have investigated the effect of prolonged creatine use during strength training. However, studies on the effects of prolonged creatine supplementation are lacking. In the present study, we have assessed the effects of both creatine loading and prolonged supplementation on muscle creatine content, body composition, muscle and whole-body oxidative capacity, substrate utilization during submaximal exercise, and on repeated supramaximal sprint, as well as endurance-type time-trial performance on a cycle ergometer. Twenty subjects ingested creatine or a placebo during a 5-day loading period (20g·day-1) after which supplementation was continued for up to 6 weeks (2g·day-1). Creatine loading increased muscle free creatine, creatine phosphate (CrP) and total creatine content (P&amp;lt;0.05). The subsequent use of a 2g·day-1 maintenance dose, as suggested by an American College of Sports Medicine Roundtable, resulted in a decline in both the elevated CrP and total creatine content and maintenance of the free creatine concentration. Both short- and long-term creatine supplementation improved performance during repeated supramaximal sprints on a cycle ergometer. However, whole-body and muscle oxidative capacity, substrate utilization and time-trial performance were not affected. The increase in body mass following creatine loading was maintained after 6 weeks of continued supplementation and accounted for by a corresponding increase in fat-free mass. This study provides definite evidence that prolonged creatine supplementation in humans does not increase muscle or whole-body oxidative capacity and, as such, does not influence substrate utilization or performance during endurance cycling exercise. In addition, our findings suggest that prolonged creatine ingestion induces an increase in fat-free mass.

Effects of creatine loading and prolonged creatine supplementation on body composition, fuel selection, sprint and endurance performance in humans.

Most research on creatine has focused on short-term creatine loading and its effect on high-intensity performance capacity. Some studies have investigated the effect of prolonged creatine use during strength training. However, studies on the effects of prolonged creatine supplementation are lacking. In the present study, we have assessed the effects of both creatine loading and prolonged supplementation on muscle creatine content, body composition, muscle and whole-body oxidative capacity, substrate utilization during submaximal exercise, and on repeated supramaximal sprint, as well as endurance-type time-trial performance on a cycle ergometer. Twenty subjects ingested creatine or a placebo during a 5-day loading period (20 g.day(-1)) after which supplementation was continued for up to 6 weeks (2 g.day(-1)). Creatine loading increased muscle free creatine, creatine phosphate (CrP) and total creatine content ( P <0.05). The subsequent use of a 2 g.day(-1) maintenance dose, as suggested by an American College of Sports Medicine Roundtable, resulted in a decline in both the elevated CrP and total creatine content and maintenance of the free creatine concentration. Both short- and long-term creatine supplementation improved performance during repeated supramaximal sprints on a cycle ergometer. However, whole-body and muscle oxidative capacity, substrate utilization and time-trial performance were not affected. The increase in body mass following creatine loading was maintained after 6 weeks of continued supplementation and accounted for by a corresponding increase in fat-free mass. This study provides definite evidence that prolonged creatine supplementation in humans does not increase muscle or whole-body oxidative capacity and, as such, does not influence substrate utilization or performance during endurance cycling exercise. In addition, our findings suggest that prolonged creatine ingestion induces an increase in fat-free mass.

Effects of creatine loading and depletion on rat skeletal muscle contraction.

1. In humans, the effects of dietary creatine supplementation are controversial, with some studies showing increased muscle force and fatigue resistance and others reporting no effect on exercise performance. Little is known about the effects of creatine on muscle contractile properties. 2. Rats were fed a standard diet, creatine for 10 days or beta-guanidinopropionate, which depletes muscle creatine, for 7 days. Contractile properties were measured in isolated extensor digitorum longus and sternohyoid muscle as representative limb and upper airway dilator muscles, respectively. 3. Creatine had no effect on specific twitch and tetanic tension, contractile kinetics, twitch/tetanus tension ratio, the tension-frequency relationship or fatigue in both muscles. beta-Guanidinopropionate had no effect on the twitch and tetanic tension, contractile kinetics, twitch/tetanus tension ratio or tension-frequency relationship, but significantly increased (P < 0.05, anova) fatigue in both muscles. 4. Therefore, although creatine depletion increases fatigue, creatine loading has no effects on extensor digitorum longus and sternohyoid muscle contractile properties.

Effect of creatine loading on anaerobic performance and skeletal muscle volume in NCAA division I athletes

OBJECTIVE: We measured the effect of 3 d of creatine (Cr) supplementation on repeated sprint performance and thigh muscle volume in elite power athletes. METHODS: Ten male (mean ± standard deviation of body mass and percentage of fat (81.1 ± 10.5 kg and 9.8 ± 3.5) and ten female (58.4 ± 5.3 kg and 15.0 ± 3.4) athletes were matched for sex and 10-s cycle sprint scores, paired by rank, and randomly assigned to the Cr or placebo (P) group. Subjects completed six maximal 10-s cycle sprints interspersed with 60 s of recovery before and after 3 d of Cr (0.35 g/kg of fat-free mass) or P (maltodextrin) ingestion. Before and after supplementation, 10 contiguous transaxial images of both thighs were obtained with magnetic resonance imaging. RESULTS: Cr supplementation resulted in statistically significant increases in body mass (0.9 ± 0.1 kg, P < 0.03), total work during the first sprint ( P < 0.04), and peak power during sprints 2 to 6 ( P < 0.10). As expected, total work and peak power values for males were greater than those for their female counterparts during the initial sprint ( P < 0.02); however, the reverse was true during the last three sprints ( P < 0.01). Imaging data showed a 6.6% increase in thigh volume in five of six Cr subjects ( P = 0.05). CONCLUSION: These data indicate that 3 d of Cr supplementation can increase thigh muscle volume and may enhance cycle sprint performance in elite power athletes; moreover, this effect is greater in females as sprints are repeated.

The effect of creatine monohydrate loading on maximal intermittent exercise and sport-specific strength in well trained power-lifters

The effect of creatine loading on the performance of sedentary and recreationally active individuals has been well documented, but research on well trained individuals is still lacking. In this double-blind study the effect of creatine monohydrate loading (9g/day) on maximal intermittent isokinetic exercise and sport-specific strength in 13 well trained power-lifters was ascertained. Both before and after supplementation the creatine (n=8) and placebo (n=5) groups performed three sets of maximal unilateral knee extensions on an isokinetic dynamometer interspaced with 60s rest periods. This was followed up the next day by a maximal deadlift strength feat performed in a gymnasium. Values for peak torque, average power, total work and work output during the first five sample repetitions in the creatine group increased significantly and in a relatively constant fashion in all subjects (correlation coefficients ranged between 0.84 and 0.92) after five supplementation days. There was also a significant ( p = 0.010) increase in the deadlift lifting volume after six days of creatine supplementation. Findings from this study suggest that nine grams of creatine monohydrate per day for five and six days respectively, improves maximal intermittent isokinetic power output and sport-specific strength in well trained power-lifters.

Effects of creatine loading and training on running performance and biochemical properties of rat skeletal muscle

Several reports have shown that the use of oral creatine (Cr) supplementation can increase performance during brief high intensity exercise in humans. The purpose of this study was to examine the separate and combined effects of Cr supplementation and high intensity run training on the performance capacity and biochemical properties of rodent skeletal muscle. Running performance was assessed following acute (10-d) and chronic (4-wk) Cr supplementation. Results indicate that Cr supplementation alone has ergogenic effects and the combination of run training plus Cr results in a more pronounced enhancement of performance than either intervention alone. The benefits of Cr supplementation were seen most clearly during repetitive bouts of high intensity interval running. Cr concentrations increased in both the slow soleus and fast plantaris muscles (P < 0.05) in response to Cr supplementation. Increased creatine concentrations appeared to be reflected in increased phosphorylated creatine (PCr). Citrate synthase (CS) activity was increased in both the soleus and plantaris muscles following training (P < 0.05). CS activity of the untrained soleus but not the plantaris responded to the dietary stimulus. There were no significant changes in either creatine phosphokinase activity or myosin heavy chain isoform distribution following training or supplementation. These results indicate that the gains in high intensity running performance seen following Cr loading are a combined result of increased aerobic (CS) and anaerobic (Cr and PCr) energy buffering capacity of the muscle.

NUTRITION NOTES: The Effect of Creatine Loading on Muscular Strength and Body Compostion

NUTRITION NOTES: The Effect of Creatine Loading on Muscular Strength and Body Compostion