Effect of snorkel use on hemoglobin saturation, 

heart rate, lactate and glycemia in fighters

Efecto del uso del snorkel en la saturación de la hemoglobina, la frecuencia cardíaca, el lactato y la glucemia en luchadores


Institute of Physical Activity Sciences and Sport

Cruzeiro do Sul University, Sao Paulo


Leandro de Lorenço-Lima, MS

Thaísa Simões Monteiro, BS

Gustavo Barquilha, MS

Marcelo Paes de Barros, PhD

Sandro Massao Hirabara, PhD







          In the world sports history the search for performance enhancement is unending. Some methods are adopted hypothetically as a way to promote positive physiological ergogenic effects. Many combat sport athletes use a snorkel, in conjunction with a nose clip, attempting to restrict the oxygen uptake and thus trigger positive physiological processes to increase performance. Twelve Brazilian jiu-jitsu athletes participated in this study. They went to the laboratory twice. The first time they performed the treadmill protocol without snorkel (CON) and after 7 days, in the second time, they performed the same protocol with snorkel (SNK). The snorkel had 1.7 cm diameter, 46 cm length, and had ¾ of the air entrance blocked. Data was collected pre-exercise (Pre), post-exercise (Post) and 1 hour post-exercise (1 h post). The SNK group presented a lower performance than the CON group which showed different HR Pre-exercise (SNK > CON) and Post-exercise (CON > SNK). Hemoglobin saturation was lower for SNK Pre and Post. Lactate was lower for SNK at Post and glycemia did not show any difference. It is possible to conclude that the snorkel implementation promoted a higher hemoglobin desaturation even with a lower performance, suggesting that it can be considered as a good strategy during certain parts of a training periodization to keep the stimulus and decrease body muscle damage promoted by training.

          Keywords: Martial Arts. Jiu-Jitsu. Ergogenic aid. Hypoxia. Air restriction.


          Receiving: 22/09/2014 - Acceptance: 05/11/2014.


EFDeportes.com, Revista Digital. Buenos Aires, Año 19, Nº 198, Noviembre de 2014. http://www.efdeportes.com/

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    Combat sports cover all modalities that involve two fighters battling for the victory, which is determined by points, loss of consciousness, submission or disqualification (Lorenço-Lima et al., 2010; Lorenço-Lima, 2011; Lorenço-Lima et al., 2011). In terms of biomechanical requirements, combat sport fighters usually combine explosive/powerful movements and long-term isometric contractions during combats. Therefore, muscle (and grip) strength, flexibility, solid tendons and stabilized joints are main motor requirements for fighting performance (López-Gullón et al., 2011). Regarding physiological and metabolic demands, glycogen storage in muscles, fast transition from lactic to aerobic metabolism (and vice versa) and, thus, sufficient oxygen supply for skeletal muscles should be smoothly coordinated in order to provide energy for movement executions during combats. Innovative training programs are now focused on the metabolic chronic stimulation of the metabolic energy demands imposed by competitive matches: basically, by activating moderately the glycolytic pathway and improving O2 supply during simulated combats (Andreato et al., 2013). Once again, trainers and physiologists reinforce the importance of O2 uptake as a key factor for fighters’ preparation for competitions.

    In many sports, physiologists and trainers accurately apply consolidated scientific evidence to support their proposed training programs. Physiological stimulation means taking the athlete out of the comfort zone and it is apparently essential for performance enhancement. However, some of these strategies are still empiric, and scientific information is still scarce. Among fighters, one very popular strategy to improve endurance is the use of a snorkel apparatus during training. Aiming to promote a systemic hypoxia, the snorkel strategy hypothetically induces oxygen uptake restriction and, therefore, partially desaturates the hemoglobin mass, promotes an increase in erythropoietin (EPO) production and release by the kidney, which is recognized by the bone marrow as a signal to increase hematopoiesis (Lorenço-Lima et al., 2011). Another hypothesis is that the oxygen restriction can increase blood acidosis by the increase of blood CO2 concentration, since both oxygen uptake and CO2 output are restricted. By controlling ventilation, the bicarbonate buffer is supposedly activated, and the anaerobic system would be more participative culminating in a higher lactate production and a lower glycemia. Since a lower O2 volume was probably sent to the muscle in activity, the heart rate (HR) would to be higher to support the O2 demand (for aerobic transition), that could be shown by a higher HR in the restricted group. Therefore, the aim of this study was to determine the effects of the snorkel strategy during maximal treadmill exercise on hemoglobin saturation, heart rate, lactate production and glycemia in Brazilian jiu-jitsu athletes.

Material and methods

    Twelve healthy men participated in this study (age: 22.20 ± 4.20 years; weight: 69.52 ± 8.19 kg; height: 173.80 ± 3.08 cm), and they were all Brazilian jiu-jitsu athletes with at least 6 months of experience. All athletes had been informed about the research details and signed a consent term approved by the Cruzeiro do Sul University Ethics Committee according to the norms of Resolution 196/96 of the National Health Council on research involving humans.

    Athletes went twice to the laboratory. In the first time they performed the treadmill protocol without snorkel for control (CON), and after 7 days they performed the same protocol equipped with a snorkel apparatus (SNK). Participants remained 48 h without exercise before the test. The snorkel had 1.7 cm diameter and 46 cm length, and had ¾ of the air entrance blocked.

    Before the exercise protocol volunteers kept themselves lying during 5 min for rest data collection and snorkel familiarization (in the second experimental set). The exercise protocol consisted of a maximal treadmill exercise: with a 2 % inclination, the speed started at 5 km/h for three min, after that 1 km/h was added until volunteers’ exhaustion (Davis et al., 1982).

    HR (Polar model RS800CX) and hemoglobin saturation (SpO2) (pulse oximeter APK Tecnologi Co., Ltd, MD300) were collected every min from 5 min before to the end of the test, and subsequently every 5 min after the test (for 1 h). Time to exhaustion, maximum speed and distance were collected. Glycemia (On Call Plus, Acon Laboratories, Inc) and lactate (Lactate Plus, Nova Biomedical) data were collected from the fingertip pre (Pre), post (Post) and one hour post exercise (1 h post).

    Data was treated in two different ways: (1) to compare groups the T Test for paired samples was selected; (2) for analysis between moments (Pre, Post and 1 h post) the ANOVA one way with Turkey’s post hoc was adopted. For these treatments the IBM SPSS Statistics 19 was used.


    Oxygen restriction promoted by snorkel resulted in a significant difference of performance between SNK and CON groups. The CON group performed 2156 (± 277.57) m during 13.60 (± 1.07) min at a pace of 15.60 (± 1.07) km/h, whereas SKN group showed lower results: 1270 (± 353.45) m during 10.60 (± 1.71) min at a pace of 12.20 (± 1.22) km/h.

    There was a significant difference between groups at Pre, where the SNK group had a higher HR, and Post, where the SNK had a lower HR. SpO2 was lower at Pre and Post for the SNK group (Table 1).

    Figure 1A shows the HR behavior for both groups, which were very similar all over the test, although SNK group was forced to precociously interrupt the treadmill test. Figure 1B shows the clear difference in hemoglobin saturation between groups during the test.

    Lactate levels increased from Pre to Post and decreased from Post to 1 h post for both groups. However, lactate concentration after the test was lower in SNK group. No difference was found in glycemia pre/post the treadmill test (Table 2).


    Studies attempting to promote performance improvements through air uptake restrictors are scarce. Acute or chronic hypoxia protocols look very efficient to increase EPO synthesis (Eckardt et al., 1989; Knaupp et al., 1992), erythroide activity and hematocrit synthesis (Ou et al., 1992). Other authors have shown that acute exposure to hypoxia in a hypobaric chamber increases the EPO production after 114 min in a 3000 m altitude simulation or 84 min in 4000 m (Davis et al., 1982). A normobaric hypoxia seems to be efficient to increase the EPO synthesis after 240 min of exposure (Eckardt et al., 1989). A fourteen consecutive-day chronic hypoxia in a 5500 m simulated altitude is capable to increase erythroide activity, hematocrit and EPO synthesis (Knaupp et al., 1992). Higher EPO concentrations are apparently efficient for increasing oxygen uptake, and this efficiency in the aerobic metabolism is due to the positive stimulus from erythropoiesis that increases the oxygen transport to the muscles (Ou et al., 1992). Furthermore, the EPO is capable to cross the hematoencephalic barrier, decreasing central fatigue and increasing cognition (Lundby et al., 2008; Rasmussen et al., 2010). However, unfortunately, hypobaric chambers are not accessible for most athletes.

    In a previous study, a hemoglobin desaturation using a snorkel with 1.7 cm diameter and 46 cm length was attempted, but no difference was found among groups with and without snorkel (Lorenço-Lima et al., 2011). The present study promoted restriction on ¾ of the air entrance, which showed few differences from the previous study.

    The Post-exercise HR difference between groups is justified by an earlier test interruption of SNK group, therefore, the SKN group was not able to achieve their maximum HR. Lorenço-Lima et al. (1011) reveled no difference in the HR between groups (Pre: 65.8 ± 9.2 and 74.4 ± 13.2 bpm; Post: 187.2 ± 9.25 and 189.8 ± 10.1 bpm; 1 h post: 85.8 ± 7.9 and 80.8 ± 10.2 bpm, CON and SNK respectively). The present study found higher HR Pre for SNK, lower Post for SNK, and similar 1 h post for both groups. Lorenço-Lima et al. (2011) did not show any difference on SpO2 (Pre: 97.2 ± 1.3 and 97.8 ± 0.8 %; Post: 91.4 ± 2.5 and 90 ± 3.93 %; 1 h post: 97.6 ± 0.8 and 96.4 ± 1.5 %, CON and SNK respectively), which is different from the present where the SpO2 was lower for SNK at Pre and Post, but not for 1 h post.

    Lactate was also not changed between groups (Lorenço-Lima et al., 2011) previously (Pre: 0.99 ± 0.07 and 0.98 ± 0.05 mmol/L; Post: 9.41 ± 1.35 and 9.09 ± 0.74 mmol/L; 1 h post: 1.00 ± 0.05 and 1.00 ± 0.04 mmol/L, CON and SNK respectively). In the present study lower lactate level for SNK was found Post compared to CON, having been justified by the lower performance of SNK.

    In the only other study using snorkel found, twelve recreational runners (6 male and 6 female) were assigned in two groups in a study that evaluated the efficiency of a six-week snorkel training on the respiratory muscles and performance in a 5-km time trial. No statistical difference was found, but, despite of it, the group suggested a practical improvement of 36 s less in the 5-km time trial with snorkel training (Johnston et al., 2011).


    It is possible to conclude that the snorkel implementation/air restriction promoted a higher hemoglobin desaturation even with a lower performance. Snorkel usage seems to be an accessible and cheap way to promote hypoxia. It suggests that it can be used as a good strategy during certain parts of a training periodization to keep the stimulus and decrease the body muscle damage promoted by high intensity training.


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