Literature DB >> 25566437

Effect of energy drink dose on exercise capacity, heart rate recovery and heart rate variability after high-intensity exercise.

Sang Min An¹, Jong Suk Park¹, Sang Ho Kim¹.

Abstract

PURPOSE: The purpose of this research was to investigate the effects of exercise capacity, heart rate recovery and heart rate variability after high-intensity exercise on caffeine concentration of energy drink.
METHODS: The volunteers for this study were 15 male university student. 15 subjects were taken basic physical examinations such as height, weight and BMI before the experiment. Primary tests were examined of VO2max per weight of each subjects by graded exercise test using Bruce protocol. Each of five subject was divided 3 groups (CON, ECGⅠ, ECGⅡ) by matched method based on weight and VO2max per weight what gained of primary test for minimize the differences of exercise capacity and ingestion of each groups. For the secondary tests, the groups of subjects were taken their materials before and after exercise as a blind test. After the ingestion, subjects were experimented on exercise test of VO2max 80% by treadmill until the all-out. Heart rate was measured by 1minute interval, and respiratory variables were analyzed VO2, VE, VT, RR and so on by automatic respiratory analyzer. And exercise exhaustion time was determined by stopwatch. Moreover, HRV was measured after exercise and recovery 3 min.
RESULTS: Among the intake groups, ECGⅡ was showed the longest of exercise exhaustion time more than CON group (p = .05). Result of heart rate during exercise according to intake groups, there was significant differences of each time (p < .001), however, not significant differences of each groups and group verse time (p > .05). Result of RPE during exercise according to intake groups, there was significant differences of each time (p < .001), however, not significant differences of each groups and group verse time (p > .05).
CONCLUSION: In conclusion, EDGⅡ showed the significant increase of exercise exhaustion time more than CON group (p=.05) and not significant differences in HR, RPE, RER, HRV, HRR, blood pressure (p > .05). Therefore, 2.5 mg/kg(-1) ingestion of energy drink might be positive effect to increase exercise performance capacity without side-effect in cardiovascular disease.

RCT Entities: Population Interventions Outcomes

Entities: Chemical Disease Gene Species

Keywords: Caffeine; Cardiovascular; Energy Drink; Exercise; HRR; HRV

Year: 2014 PMID： 25566437 PMCID： PMC4241927 DOI： 10.5717/jenb.2014.18.1.31

Source DB: PubMed Journal: J Exerc Nutrition Biochem ISSN： 2233-6834

INTRODUCTION

Necessity and purpose of the study

Among energy drinks available in Korean market, ‘Hot Six,’ an energy drink from Lotte Chilsung, marked 250 million won sales in Jan. 2011. Since 2012, its sales have recorded more than 3 billion won every month, indicating rapid growth of energy drink market in Korea. A sales analysis on the market showed that energy drinks are sought mostly by young people - those in their teens and 20s accounted for 23% and 41% of the consumers respectively. Energy drinks are known to boost mental and physical energy of those who drink them [1]. Caffeine, taurine and citric acid are considered primary ingredients that boost mental and physical energy in consumers [2]. The primary ergogenic ingredient in the drinks is known to be caffeine [3]. The caffeine level in energy drinks makes a whole lot of difference [4]. Caffeine is readily accessible in everyday life and consumed through various drinks and foods [5,6]. However, too much caffeine consumption can cause a range of side effects - anxiety, insomnia, accelerated heartbeat, caffeine addiction, caffeine withdrawal, etc. [7]. Considering these adverse effects, Korea’s Ministry of Food & Drug Safety made caffeine content warning label mandatory for all drinks except green tea and coffee. The label warns people that beverages containing more than 0.15 mg/mL level of caffeine are classified as a high caffeine drink and should be avoided by those sensitive to caffeine such as children and pregnant woman [8]. When caffeine is absorbed in the body, it stimulates sympathetic nervous system and results in a rise in plasma catecholamine that allows the body to adapt to the stress created by physical exercise. In the heart, it prompts secretion of norepinephrine and epinephrine to increase the rate and force of the muscle’s contractions. They raise the rate and force of the heart, thereby increasing the blood pressure and make the heart beat faster [9]. Catecholamine production increases the availability of free fatty acids as muscle substrates during work, thus allowing glycogen sparing, improving physical performance [10,11]. Since Costill et al. [12] reported the improvement of physical performance after intake of caffeine, many studies have reported the same and claimed that ergogenic effect of caffeine was seen in people who had at least more than 2.5 mg/kg-1. dose of caffeine intake [13,14]. However, caffeine intake of more than 3 mg/kg-1 or 200 mg/kg-1 resulted in side effects such as stomach pain, anxiety, hypersensitiveness, faster heartbeats, etc. [15]. As concerns grow bigger over increasing caffeine intake due to increasing consumption of energy drinks, studies that investigate the effects of caffeine intake on physical performance within the safe caffeine limit that would not cause side effects is needed. Also, dose of caffeine intake needs to be analyzed by physique of each person in order to ensure safety and establish systematic data. Thus, this study intends to analyze the effects of caffeine-containing energy drink consumption on physical performance during high intensity exercise and hear rate recovery (HRR) and heart rate variability (HRV). It also aims to Fig. out the dose of caffeine intake which may improve physical performance without triggering side effects.

METHODS

Subjects

15 male students at Department of Social Physical Education of K University became the subjects of this study. In order to make sure that participants’ in each group are similar in their VO2max, height, weight, etc., matching methods were used to group the 15 participants into three groups (5 per each group) - control group that drank water without caffeine (0 mg/kg-1 caffeine), ECG (energy consumption group)Ⅰthat drank energy drinks with 1.25 mg/kg-1 dose of caffeine and ECG (energy consumption group) Ⅱ that drank energy drinks with 2.5 mg/kg-1. Physical characteristics of the participants is summarized in the .

Table 1.

Physical characteristic of subjects

Group	n	Age (yrs)	Height (cm)	Weight (kg)	BMI (kg/m²)	VO₂max (mL/kg/min)
CON	5	21.20±1.79	177.60±6.54	72.20±4.09	23.20±1.64	57.20±10.76
ECG I	5	21.40±1.14	177.60±4.39	73.20±5.22	23.40±1.14	59.20±5.63
ECG II	5	20.20±0.45	175.20±5.27	72.60±4.04	23.40±0.89	59.60±2.88

F		1.319	.312	.063	.042	.159
P		.303	.738	.939	.959	.855

Values are Mean ± Standard deviation

CON : control group, ECG I: energy drink 1.25 mg/kg-1 consumption group, ECG II: energy drink 2.5 mg/kg-1 consumption group

Measuring instruments and methods

Measurement of physiques

Subjects were not allowed to eat or exercise for six hours before the test and they were told to urinate and defecate before the test. They wore shorts and short sleeve T-shirt when measuring their height using a height machine (Health mate 9600A, Sewoo, Seoul, Korea) and weight and body composition with body composition analyzer (Inbody 720, Biospace, Seoul, Korea).

Exercise load method

In order to serve the purpose of this study, two tests - preliminary test and primary test -were conducted at one-week interval in a way to get rid of any possible influence. All subjects were told not to drink alcohol or caffeinated drink or food on the previous day. They fasted for six hours before the tests which were conducted at the same time of the day. Subjects arrived at the test room two hours before the test and had their body composition measured and sat on chairs until the test. Burce protocol was used to measure their VO2 max while they ran on treadmill (Cosmed T150, Rome, Italy) until they reach their maximum, Automatic metabolic gas analyzer (Tru One 2400, Parvo Medics, UT, USA) was used to measure gas during exercise. A 5-minute warm-up - starting from 1.7mph to gradually reach less than 70% of VO2 max - was conducted based on a study by Darren et al. [16] and then each subject ran at 80% of his/her VO2 max. Respiratory parameters, heart rate, and rating of perceived exertion (RPE) were checked every minute during the exercise. Gas analysis data, heart rate, respiratory index, etc. displayed on the monitor were checked while subjects were exercising. They were told to stop exercise when they reached 90% of their maximum predicted heart rate (220-age) or exceeded a respiratory exchange ratio of 1.15. Subjects were told to walk for 60 seconds at 1.2 mph after stopped running and sat on chairs to monitor changes in their records. All tests were done in the same condition - room temperature of 22 - 25°, relative humidity 45 ± 5%.

Ingredients of energy drinks and caffeine intake

The Vaults of Erowid - an online library containing tens of thousands of pages of information about psychoactive drugs, plants, and chemicals - classified the caffeine intake into four: minimal intake (10 m-20 mg), normal intake (50 - 100 mg), high intake (150 - 400 mg), and large intake (more than 400 mg). And a study by Reissig et al. [15], Graham et al. [17] said that caffeine intake of more than 3 mg/kg-1 or 200 mg/kg-1 resulted in side effects such as stomach pain, anxiety, hypersensitiveness, faster heartbeats, etc., Thus, we chose two caffeine doses between 3 mg/kg-1and 200 mg/kg-1. Amount of ingredients in the two energy drinks (Hot6, Hot6 light) were made same except for caffeine (30 mg, 60 mg respectively) in order to differentiate the caffeine intake by weight of each subject. In order to get the appropriate caffeine intake, we’ve used a formula - (weight × caffeine intake)/caffeine concentration. For ECGⅠ, 91.50 ± 6.52 mg of caffeine were used, while 181.5 ± 10.09 mg of caffeine were used for ECGⅡ. Amount of normal intake and high intake were chosen within the range that would not trigger side effects (between 85.25 mg and 192.43 mg). Caffeine was put into the drinks using beakers and droppers. The subjects drank the beverage 60 minutes before the tests.

Measurement of heart rate

Heart rate was measured by Telemeter Heart Checker (RS 100, Polar, Finland) before and during the exercise at 1 minute interval. The rate was also checked 1, 2, and 3 minutes after the exercise.

Measurement of blood pressure

Blood pressure was measured by a digital blood pressure monitor (model412 Quinton Co., USA) before and two minutes after the exercise in order to compare the effects of each dose of caffeine on blood pressure before and after the exercise.

Measurement of HRV

HRV (heart rate variability) was measured by SA3000P (Medicore. Co., Seoul, Korea) for five minutes before and 60 minutes after drinking the energy drinks and also after the exercise in order to compare the effects of each dose of caffeine on HRV before and 60 minutes after drinking the energy drinks and after the exercise. The subjects were told not to move or talk during the measurement. Based on the limb leads, electrodes were placed at three locations: left arm, left leg and right leg.

Data analysis

Data from this study were analyzed by SPSS/pc 20.0 Statistics for Windows in order to calculate mean deviation and standard deviation of each variable. Homogeneity test was conducted on subjects of each group to make sure their physical characteristics and exercise performance ability were similar to each other. Also, one-way ANOVA was conducted to identify different exercise time between the groups. Two-way repeated measure ANOVA was conducted to identify different heart rate, RPE, respiratory variables checked at each measurement time. The two-way repeated measure ANOVA was also used to identify difference between heart rate and HRV checked before and after the exercise. When differences were found in main effect, one-way ANOVA was used to analyze differences between each group at each measurement time. When significant differences were found between measurement times, Tukey post hoc was used to follow-up with the group factor. ɑ = 0.05 was classified to have statistical significance.

RESULTS

Difference of exercise performance ability between groups

Difference of exercise time between groups

Results from the one-way ANOVA showed a significant increase of exercise time in ECGⅡ than the control group as shown in the (p = 0.05).

Table 2.

The difference of exercise time between groups

Group	Exercise time (s)
CON (a)	474.80±72.31
ECG I (b)	608.20±118.97
ECG II (c)	672.40±141.05

F	3.880
p	.05
post hoc	a<c

Values are Mean ± Standard deviation

CON : control group, ECG I: energy drink 1.25 mg/kg-1 consumption group, ECG II: energy drink 2.5 mg/kg-1 consumption group

Difference of heart rate between groups during exercise

The two-way repeated measure ANOVA was conducted to find out the difference of heart rate between groups and measurement time. It showed a significant difference between measurement times (p < 0.001), but not between groups (p > 0.05). No interaction between groups and measurement times was found either (p > 0.05). Difference of respiratory variables between groups is shown in the .

Table 3.

The difference of heart rate between groups during exercise (unit : beat/min)

Group	Rest	During exercise						HR max
Group	Rest	1 min	2 min	3 min	4 min	5 min	6 min	HR max
CON	59.80±7.70	157.00±6.78	169.80±9.12	173.60±10.67	179.20±10.43	183.20±10.57	184.00±13.84	190.00±10.79
ECG I	57.00±6.96	158.80±9.28	168.40±4.16	169.60±8.47	176.20±2.17	177.60±5.41	180.40±4.16	186.00±5.39
ECG II	61.00±2.92	159.20±11.32	172.40±9.91	178.40±7.60	182.40±6.23	187.00±6.12	186.20±10.62	194.20±7.26

Values are Mean ± Standard deviation

CON : control group, ECG I: energy drink 1.25 mg/kg-1 consumption group, ECG II: energy drink 2.5 mg/kg-1 consumption group

Group	During exercise
Group	1 min	2 min	3 min	4 min	5 min	6 min
CON	11.20±1.10	12.60±0.89	14.60±1.67	15.40±1.67	16.60±2.19	17.00±2.00
ECG I	12.20±1.10	13.80±1.10	14.20±1.10	15.40±1.67	16.20±1.10	16.20±1.10
ECG II	11.80±1.10	12.60±1.67	14.00±2.00	14.80±1.10	15.20±1.48	15.40±1.52

	Group	During exercise						Max
	Group	1 min	2 min	3 min	4 min	5 min	6 min	Max
VO₂ (mL/kg/min)	CON	20.34±3.89	31.06±4.38	47.24±5.98	50.50±5.96	53.28±6.65	54.72±6.38	56.18±5.68
	ECG I	23.32±3.80	30.72±3.53	45.58±2.65	50.48±3.78	54.34±2.35	54.78±4.12	60.78±7.45
	ECG II	20.08±2.13	30.88±2.50	45.24±3.24	46.26±16.84	54.48±3.12	55.96±4.74	62.92±7.17

VE (L/min)	CON	32.81±5.05	45.97±7.78	78.73±14.65	98.01±13.37	107.02±16.27	112.68±18.58	125.93±16.77
	ECG I	40.66±5.65	52.29±9.04	74.54±9.68	92.64±7.60	103.14±10.17	105.94±10.60	131.69±13.57
	ECG II	38.89±9.13	50.76±7.20	77.60±9.63	95.25±12.65	98.64±11.69	113.21±12.96	131.33±10.75

VT (L)	CON	1.68±0.45	2.20±0.38	2.97±0.80	3.14±0.70	3.18±0.52	3.08±0.40	3.21±0.47
	ECG I	1.71±0.38	2.20±0.40	2.87±0.62	3.22±0.66	3.44±0.72	3.24±0.62	3.54±0.75
	ECG II	1.63±0.54	2.09±0.68	3.07±0.85	3.42±0.72	3.34±0.72	3.29±0.65	3.42±0.65

RR (beat/min)	CON	20.20±3.27	21.00±2.35	27.40±5.86	32.20±6.61	34.20±6.30	36.80±4.87	40.80±5.72
	ECG I	24.20±4.44	24.20±4.09	26.60±4.45	29.60±5.51	30.80±6.18	33.40±6.35	43.60±8.85
	ECG II	26.80±13.50	27.00±11.90	27.80±11.95	29.40±10.21	31.00±9.46	35.80±9.07	43.00±3.00

Group	Before intake	60min after intake	Max	1 min after exercise	2 min after exercise	3 min after exercise
CON	59.80±7.70	64.40±6.35	190.00±10.79	164.20±5.93	118.40±7.13	105.40±7.02
ECG I	57.00±6.96	59.40±7.60	186.00±5.39	159.00±3.32	123.20±5.36	103.60±5.27
ECG II	61.00±2.92	64.40±3.65	194.20±7.26	167.80±5.59	127.00±11.05	109.00±8.37

Group	Before intake		60min after intake		After exercise
Group	SBP	DBP	SBP	DBP	SBP	DBP
CON	111.20±4.66	67.80±9.71	112.80±7.12	65.80±6.94	136.40±8.14	65.80±7.33
ECG I	122.00±10.79	71.00±13.00	126.40±9.97	66.40±11.04	149.20±24.75	65.00±7.58
ECG II	121.40±9.02	72.60±5.86	120.60±10.41	69.00±7.58	153.40±16.23	69.60±7.37

HRV	Group	Result
HRV	Group	Before intake	After intake	After exercise
SDNN (ms)	CON	68.52±26.77	70.79±33.58	14.27±4.96
	ECG I	62.71±20.84	54.00±17.51	11.70±3.53
	ECG II	43.20±12.72	63.15±20.10	10.04±4.19

RMSSD (ms)	CON	62.06±37.65	53.19±22.68	4.90±2.07
	ECG I	61.27±20.71	58.60±22.71	4.23±0.85
	ECG II	31.61±13.97	46.61±19.29	4.00±1.03

TP (ms2)	CON	8.01±0.97	8.28±10.5	4.46±0.98
	ECG I	8.05±0.78	7.56±0.52	4.00±0.41
	ECG II	6.83±1.00	7.93±0.85	3.55±0.42

VLF (ms2)	CON	7.18±0.81	7.27±0.68	4.03±0.91
	ECG I	7.28±1.04	6.28±1.33	3.58±0.48
	ECG II	5.76±0.89	7.17±1.43	3.26±0.67

LF (ms2)	CON	6.43±0.98	7.43±1.42	3.08±1.37
	ECG I	6.65±0.59	6.20±0.23	2.53±0.52
	ECG II	5.62±1.29	6.09±0.79	1.89±0.65

HF (ms2)	CON	6.67±6.44	6.16±0.74	1.47±0.66
	ECG I	6.44±1.10	6.27±0.78	1.04±0.56
	ECG II	5.35±1.24	6.23±0.80	0.68±0.47

LF Norm	CON	46.00±25.29	74.73±14.48	84.92±9.49
	ECG I	54.29±21.62	48.21±21.96	84.27±8.01
	ECG II	56.26±19.09	47.86±23.34	78.49±8.27

HF Norm	CON	25.23±11.28	25.27±14.48	15.08±9.50
	ECG I	45.71±21.62	51.79±22.00	15.73±8.01
	ECG II	43.74±19.09	52.14±23.34	21.51±8.27

LF/HF ratio	CON	1.26±1.16	2.61±1.13	5.40±4.38
	ECG I	1.76±1.60	1.32±1.22	4.36±1.79
	ECG II	1.68±1.17	1.25±0.96	4.40±2.47

Effect of energy drink dose on exercise capacity, heart rate recovery and heart rate variability after high-intensity exercise.

INTRODUCTION

Necessity and purpose of the study

METHODS

Subjects

Measuring instruments and methods

Measurement of physiques

Exercise load method

Ingredients of energy drinks and caffeine intake

Measurement of heart rate

Measurement of blood pressure

Measurement of HRV

Data analysis

RESULTS

Difference of exercise performance ability between groups

Difference of exercise time between groups

Difference of heart rate between groups during exercise

The difference of RPE between groups during exercise

The difference of respiration variables between groups during exercise

Difference of variables between groups before and after exercise

Difference of heart rate recovery between groups

The difference of blood pressure between groups

The difference of heart rate variability between groups

DISCUSSION

1. Enhancement of 2000-m rowing performance after caffeine ingestion.

2. On- and off-responses of heart rate to exercise - relations to heart rate variability.

3. The cardiac output in rest and work at low and high oxygen pressures.

4. Twenty four hour heart rate variability: effects of posture, sleep, and time of day in healthy controls and comparison with bedside tests of autonomic function in diabetic patients.

5. Importance of arterial pulse pressure as a predictor of coronary heart disease risk in PROCAM.

6. Caffeine: a double-blind, placebo-controlled study of its thermogenic, metabolic, and cardiovascular effects in healthy volunteers.

7. Effect of different protocols of caffeine intake on metabolism and endurance performance.

8. Effect of Red Bull energy drink on repeated Wingate cycle performance and bench-press muscle endurance.

9. Metabolic, catecholamine, and exercise performance responses to various doses of caffeine.

10. Effect of sugar-free Red Bull energy drink on high-intensity run time-to-exhaustion in young adults.

Review 1. Energy Drinks and Their Impact on the Cardiovascular System: Potential Mechanisms.

2. Acute Effects of Energy Drink on Autonomic and Cardiovascular Parameters Recovery in Individuals with Different Cardiorespiratory Fitness: A Randomized, Crossover, Double-Blind and Placebo-Controlled Trial.

Review 3. Acute effects of caffeine-containing energy drinks on physical performance: a systematic review and meta-analysis.

4. Acute Specific Effects of Caffeine-containing Energy Drink on Different Physical Performances in Resistance-trained Men.

5. Caffeine affects autonomic control of heart rate and blood pressure recovery after aerobic exercise in young adults: a crossover study.

6. The effects of varying doses of caffeine on cardiac parasympathetic reactivation following an acute bout of anaerobic exercise in recreational athletes.