For this journal club we looked at the following journal article:
What was the aim of the paper?
The aim of the paper was to look at the efficacy of intermittent hypoxic training at 95% of lactate threshold on endurance performance and aerobic capacity in cyclists. The authors did not include a hypothesis. The research was carried out by scientists at the Jerzy Kukuczka Academy of Physical Eduction in Poland.
What did the study involve?
The researchers recruited 20 male elite cyclists and randomly divided them into a hypoxia (H) group (who trained in a normobaric hypoxic environment, O2= 15.2%) and a control group (normoxia environment). The experiment consisted of baseline testing, followed by three weeks of progressive training and one week recovery in which the training load was significantly reduced, and then post-testing. The testing involved taking resting blood samples, body mass and body composition. This was then followed by a progressive cycle ergometer test to determine VO2max and lactate threshold and the researchers measured heart rate, minute ventilation, oxygen uptake and expired carbon dioxide. After 24 hour rest, the participants performed a 30km time trial and heart rate, blood lactate, speed, cadence and power were measured. The training programme was the same for both groups and involved three sessions per week with a 15 minute warm-up, 30-40 minutes of core training (30 min at 95% lactate threshold workload in 1st week, 35 min in second week and 40 min in third week) and a 15 minute cool down. Intensity for the control group was 100% of lactate threshold workload.
What were the main results?
The researchers results showed that after the three week training period, there was a significant increase in VO2max, maximum workload and lactate threshold workload during the incremental test in the hypoxia group compared to the control group. The results also indicated a significant reduction in the time of the trial and a significant increase in average generated power and speed during the time trial in the hypoxia group. However, there was no difference in red blood cell count, haemoglobin concentration and haematocrit value. The authors conclude that intermittent hypoxic training at lactate threshold intensity improves aerobic capacity and endurance performance at sea level.
What can we take from it?
I enjoyed reading this paper and agree with Ben that it had some very interesting points. The research question was focussed and the study design was suitable for the research question, but it was unfortunate that they did not include a hypothesis.
The main point that I want to highlight is that the researchers did not use a repeated measures, crossover design and therefore the participants did not serve as their own control, which means that the groups could have been unbalanced and it may have introduced bias to the results. The training period of three weeks was fairly short, but the training sessions were quite long (around an hour) and at a high intensity, which may not be suitable for the general population. However, as Carla mentions, a three week training programme that improves sea level performance could be appealing to athletes to gain a competitive edge.
I’ve picked out the following comments about the research.
- The paper fails to find any changes to haematological parameters, suggesting that this intervention was not harsh enough to bring about significant erythropoiesis.
- Future research should use the same intervention, but have more follow-up analysis and include muscle biopsies to measure for changes in skeletal muscle.
- The only problem I can see with the present study is that the training only went for 3 weeks, it does not state what type of program the athletes come off, as a supercompensation effect could have accounted for the increases in power, lactate threshold and such.
- This paper highlights that hypoxia is a complimentary tool to training and not the primary stimulus.