Maurten and Gruppo Sports Drink Review

by Paul McKenzie and TCR Sport Lab 

Faculty of Kinesiology, University of Calgary

Introduction

It is well recognized in the literature that carbohydrate (CHO) supplementation during exercise enhances performance (Stellingwerff & Cox, 2014). In exercise one hour or less, although muscle glycogen is not generally limiting to performance, there is evidence that oral exposure to CHO, either through a mouthwash or drink, enhances performance due to stimulation of areas of the brain responsible for pleasure and reward (Stellingwerff & Cox, 2014). For longer duration exercise, in which muscle glycogen stores are stressed, performance is enhanced due to enhanced plasma glucose levels resulting in increased rates of CHO oxidation (Stellingwerff & Cox, 2014). In these prolonged exercise situations, evidence also supports the use of multi-transportable CHOs, such as glucose: fructose or maltodextrin: fructose blends, since they utilize multiple glucose transporters within the intestine.

Current recommendations for CHO intake during physical activity are as follows. For exercise <30 minutes, no carbs are required (Jeukendrup, 2011). In exercise ranging from 30-75 minutes, small amounts of multi-transportable carbs are recommended via mouth rinses (Jeukendrup, 2011). For exercise 1-2 hours long, up to 30g CHO/hr, and for 2-3 hours long, up to 60g CHO/hr is recommended with single carbs being okay, but multi-transportable carbs being optimal (Jeukendrup, 2011). For exercise >2.5 hours, up to 90g/hr of multiple transportable CHO, such as combining glucose with fructose, is recommended (Jeukendrup, 2011).

Unfortunately, although CHO supplementation is associated with improved performance, high CHO intake during exercise has been linked to gastrointestinal (GI) distress, with higher scores of nausea and flatulence (Pfeiffer et al., 2012). GI distress is common in endurance events, with 30% of Ironman athletes reporting serious GI distress during their races, while only 4% of marathon racers and cyclists reported serious GI distress (Pfeiffer et al., 2012).

To combat this, a supplement was developed with the aim of allowing high doses of CHO during exercise to athletes with reduced amounts of GI distress. The product includes a multi-transportable CHO mix (maltodextrin and fructose), with the addition of sodium alginate and pectin, which forms a hydrogel structure in low pH environments, such as the stomach. This hydrogel encapsulates the carbohydrates which blocks duodenal receptors that prevent gastric emptying and can cause gastrointestinal discomfort (Baur et al., 2019).

Although many elite athletes, such as marathon superstar Eliud Kipchoge, publicly swear by and support this product, the scientific evidence proving the products benefit is mixed (Hutchinson, 2019). An abstract presented at the American College of Sports Medicine meeting in 2019 reported that half of the ingested drink with sodium alginate and pectin was emptied in 21.2 minutes, compared to 36.3 minutes for the same drink without sodium alginate and pectin, supporting the companies claim that the CHO surrounded by the hydrogel is an effective method to improve gastric emptying (Sutehall et al., 2019).

Purpose

The purpose of this study is to evaluate the effect of consuming a drink mix or gel containing CHO with sodium alginate and pectin on performance, oxygen consumption, rate of perceived exertion, blood glucose and lactate concentration, and respiratory exchange ratio (RER), and GI distress during a cycling or walking/running 60-minute steady state test followed by a ramp incremental test.

Methods

Participants

Three participants were recruited from this study. Subject 1 was a 43-year-old male whose modality of choice was biking, Subject 2 was a 31-year-old female whose modality of choice was walking/running on a treadmill, and Subject 3 was a 35-year-old male whose modality of choice was biking. Participants were all staff at the location in which the study took place.

Experimental Procedure

Participants were asked to arrive in the lab in a natural state and were asked to match this state as much as possible from trial to trial.

The bike tests were performed on a Velotron electronically braked bike, while the treadmill tests were performed on a Woodway Desmo Pro.

 The experimental procedure consisted of riding or walking at a self-selected pace corresponding with around 60% of VO₂max for 60 minutes while consuming the experimental beverages as described below, followed by a ramp incremental test (RIT). For the RIT, the cyclists began at their steady state power output, and this was increased by 20 W/min until the participants could no longer maintain their cadence or the participant could not go any further. The treadmill RIT began at the same speed and incline as the steady state, and increased by .5 mph and .5% incline, alternating speed and incline until the participant could not go any further.

For the steady state portion, Subject 1 rode at 220W, Subject 2 walked at 3.0 mph at an incline of 7.0%, and Subject 3 rode at 200 W.

VO₂, carbohydrate, and fat oxidation was measured throughout the steady state and RIT using a Parvo Medics Metabolic Cart. Heart rate was recorded using a POLAR chest strap monitor either throughout the test or at the 0, 15, 30, 45, 60, and end of RIT time points. Rate of perceived exertion (RPE) and GI Distress both used a scale of 0-10 with 0 being no distress and 10 being the worst distress possible and were measured at each of the time points described above. Blood glucose was measured using a Accu-Chek glucose monitor, and Lactate was measured using a Nova Biomedical Lactate Plus Analyzer at each of the time points described above, using a finger prick blood draw.

Experimental Beverages

At time points 0, 15 min, 30 min, and 45 min, participants consumed 125mL of the carbohydrate mix, for a total of 500 mL of mix for each trial. During the Maurten trial, participants consumed the 320 Drink Mix, totalling 79g of carbohydrates (with sodium alginate and pectin), or 19.75g of carbohydrates every 15 minutes. During the Gruppo trial, participants consumed 1 scoop of Gruppo Ride Endurance fuel, totalling 32.4 g of carbohydrates, or 8.1g of carbohydrates every 15 minutes.

 

Results

Summary of one of the riders in the study:

		Pre	15 Min	30 Min	45 Min		End of Ramp
	Product					60 Min
VO2	Maurten	-	2.74	2.61	3.01	2.89	3.73
(L/min)	Gruppo	-	3.08	3.17	3.09	2.84	4.14
HR	Maurten	-	140	148	155	163	181
(bpm)	Gruppo	-	155	157	159	161	181
La-	Maurten	1.4	4.5	4.9	4.2	4	12.3
(mmol/L)	Gruppo	-	4.6	3.2	3.7	10.4	7.3
Blood Gluc.	Maurten	4.7	4.8	5.6	4.9	5	5.5
(mmol/L)	Gruppo	4.3	4.3	4.9	4.5	4.9	5
RER	Maurten	-	0.98	0.94	0.98	0.99	1.2
	Gruppo	-	0.94	0.95	0.96	0.97	1.1
RPE	Maurten	-	4	4	6	6	10
(/10)	Gruppo	-	3	4	4	7	10
GI Discomfort (/10)	Maurten	0	0	0	0	0	0
	Gruppo	0	0	0	0	0	0
Carbohydrate Ingested	Maurten	20g	20g	20g	20g
	Gruppo	8.1g	8.1g	8.1g	8.1g

Discussion

Taken together, the results of all three participants do not support a clear answer that either product is superior to one another. Participants 2 and 3 had better performances with the Maurten mix, while participant 1 performed better with the Gruppo mix, although they did state they thought this was due to the training effect rather than the drink consumed.

In terms of gastrointestinal distress, participant 1 and 3 did not sustain any gastrointestinal distress in either trial, contrary to the literature suggesting that excessive carbohydrate consumption may result in GI distress (Pfeiffer et al., 2012). This supports the claims that the hydrogel that encapsulates the high carbohydrate load in the Maurten mix aids in reducing gastrointestinal discomfort (Baur et al., 2019). 

Limitations

            It is important to recognize and consider the limitations of the study. Firstly, although we asked participants to keep their food intake and drink consumption similar between trials, it was not strictly controlled, meaning the intake around the trial may have influenced performance, although it would still have been representative of everyday training, as opposed to a strictly controlled lab setting. Furthermore, the participants all performed the Gruppo trial following the Maurten mix, meaning either a training or detraining effect may have been seen in some of the participants. Finally, it is important to recognize that our sample size is very small (n=3), and because of this, the results may not be generalizable to the general population, and instead may be more representative of individual differences.

Future Directions

            Future studies should continue to look into the effect of consuming carbohydrates with a hydrogel structure to prevent GI distress and compare the results to other products to help athletes decide which sports performance drink may help them the most in the competition. Repeating this study with a larger sample size in a more controlled environment could paint a clearer picture about which product may aid performance more.

Conclusion

            In summary, we found no clear differences in performance and GI symptoms between trials when the participants ingested the Maurten mix compared to the Gruppo mix. Our findings support the idea the hydrogel in the Maurten mix may help prevent GI distress during cycling and walking, although the length of the trials may not have been long enough to observe these symptoms.

 

Main Findings from a Coach's perspective

Maurten was 20g / 15 min or 320 calories per hour and Gruppo was 8.1g / 15 min or 130 calories per hour.  However, even though Maurten had over double the carbohydrate intake of Gruppo, the subject's blood sugar still remained equal and steady when compared to the lower carbohydrate intake.  It's like drinking a can of Coke without the sugar high. 

The goal of endurance sport is to be able to hold pace over the 2 hour mark and often longer.  Many endurance races are 4 hours plus, but the body has only 2 hours of glycogen to use.  This reserve of glycogen dissipates quickly if you are working hard without more carbohydrate coming in.  Eating solid foods in the 320 calorie range per hour is difficult to do due to the act of chewing, slow digestion and sometimes it is impossible in fast races or sports like mountain biking.  Liquid drinks are fast and easy to digest comparatively. 

The advantage of the Maurten drink is that you ingest a significant amount of carbohydrate that typically would cause indigestion and blood sugar spikes.  From a fuelling perspective, your body's glycogen stores are not depleted so quickly allowing a prolonged pace with less fatigue.  This then explains some of the extraordinary efforts elite athletes are able to achieve in races nowadays.  The best testimonial we have to date is customers coming into our store and pointing at the Maurten product and saying "I want that stuff, it really works!"