Bigger Triceps in 8 Weeks of Reduced Oxygen Training - "Bigger" as in "Bigger Than With Regular 10-RM Training

Please, do me a favor and read the info in the red box. Hypoxia ≠ Kaatsu

Assuming that you've read the headline of this article first, you should already have realized what makes this study special: A realistic training regimen that's relevant for to the "average gym context". "10 reps to failure" - and that is actually pretty close to what the average trainee does on one of his / her "arm days" at the gym.

Against that background I can live with the minor downside that the subjects were 13 healthy men (mean age, 23 years; height 169 cm; body mass 60 kg) who were assigned to train either under normoxic or hypoxic training conditions were a little "too average" (=untrained) for my liking.
As the well-read SuppVersity student you've become ever since you've been reading these articles, you will obviously know that using noobs as your subjects is something exercise scientists like to do, because they know that this helps them to avoid null-results, as they tend to occur in in studies with trained subjects, simply the study duration was too short and / or the training intensity too pathetic to measure significant changes in any of the outcome variables.
As the data in Figure 1 goes to show you, neither (a) nor (b) nor both was the case in the study at hand. The Elbow extensions the subjects performed at a workload of a 10 RM with the non dominant arm to exhaustion three times with 1-minute intervals 3 days each week for 8 weeks, did after all elicit significant strength and size gains in both groups - regardless of whether they were performed while the subjects were inspiring normoxic air (FiO2=20. 9%; at sea level) or hypoxic gas (FiO2=12 .7%; corresponding to 4000 m above sea level):

Figure 1: Thickness of triceps brachii (a and b) in both arms before and after training in the normoxic (N) and hypoxic (H) groups; ** denotes significant difference (Kurobe. 2014)

The overall changes in size and strength are yet luckily not the only significant effect, the researchers from the National Institute of Fitness and Sports in Japan observed in their study.

The inter-group differences, i.e. the significantly greater increase in muscle thickness the hypoxia group, was significant, as well. And while the latter cannot be said of the increase in strength, I am pretty sure that the additional size gains alone would be reason enough for some of you to take a bottle with reduced oxygen air (Fi=2=12.7%; meaning only 12.7% of the air in the container would be oxygen to the gym).
References:

• Kurobe et al. "Effects of resistance training under hypoxic conditions on muscle hypertrophy and strength." Clin Physiol Funct Imaging(2014) doi: 10.1111/cpf.12147