Popeye was right, spinach (combined with interval training) can enhance fitness, after all

Interval sprinting: the ultimate exercise

It is now well-known that the most effective method of exercise, both for weight loss and for fitness development, is sprint interval training. Sprint interval training includes interval running, interval swimming, interval cycling and interval rowing and uphill/downhill walking among others.


Nitrates boost the effectiveness of interval training

In this study published last June, it was found that nitrates, such as those found in spinach and beetroot, can improve sprint interval training performance and can even turn slow twice fibres to fast twice ones!

This is a significant breakthrough, given that as people age the natural tendency is to lose fast twice fibres, which convert into slow twice ones.

For this study, averagely fit individuals performed 4-5 sprints per session, three times a week, in hypoxic (low oxygen) conditions. These conditions replicate training in high altitude, known to be beneficial for both sprint and endurance athletes.

The all-out sprints were of 30-second duration, interspersed by 4½ minutes of recovery intervals (these typically consist of slow walking).

The volunteers who took nitrate capsules 3 hours before each session, saw increased growth of type IIa (fast twitch) muscle fibres, while volunteers training without the nitrates or under normal oxygen levels saw no such improvement.

A higher percentage of fast twitch fibres means an increased printing capacity and increased muscle strength. Indeed, the volunteers who took the nitrate supplement had better performance than the other groups.

On the other hand, maximum oxygen use (VO2max) and endurance training performance increased equally in all groups. This shows that neither nitrates nor hypoxic sprint training gives an edge in endurance training, both of which were to be expected.


Spinach, beetroot and green salads fight hypoxia - and cellulite

So all in all, nitrates seem to increase strength and sprinting fitness, especially when combined with hypoxic training - as Popeye always knew ;)

Given the anti-hypoxic effect of nitrates, we can deduce that spinach, green salads and other nitrate-rich foods are ideal as cellulite-preventing foods (hypoxia is an important cause of cellulite).

Sprint interval training is also known to be the absolute best anti-cellulite exercise, due to it's effect on metabolism, circulation and fat burning, so having spinach smoothies and doing interval training may not just improve athletic performance but also fight cellulite.



  • Paper: Nitrate Intake Promotes Shift in Muscle Fiber Type Composition during Sprint Interval Training in Hypoxia
  • Abstract: Purpose: We investigated the effect of sprint interval training (SIT) in normoxia, vs. SIT in hypoxia alone or in conjunction with oral nitrate intake, on buffering capacity of homogenized muscle (βhm) and fiber type distribution, as well as on sprint and endurance performance. Methods: Twenty-seven moderately-trained participants were allocated to one of three experimental groups: SIT in normoxia (20.9% FiO2) + placebo (N), SIT in hypoxia (15% FiO2) + placebo (H), or SIT in hypoxia + nitrate supplementation (HN). All participated in 5 weeks of SIT on a cycle ergometer (30-s sprints interspersed by 4.5 min recovery-intervals, 3 weekly sessions, 4–6 sprints per session). Nitrate (6.45 mmol NaNO3) or placebo capsules were administered 3 h before each session. Before and after SIT participants performed an incremental VO2max-test, a 30-min simulated cycling time-trial, as well as a 30-s cycling sprint test. Muscle biopsies were taken from m. vastus lateralis. Results: SIT decreased the proportion of type IIx muscle fibers in all groups (P < 0.05). The relative number of type IIa fibers increased (P < 0.05) in HN (P < 0.05 vs. H), but not in the other groups. SIT had no significant effect on βhm. Compared with H, SIT tended to enhance 30-s sprint performance more in HN than in H (P = 0.085). VO2max and 30-min time-trial performance increased in all groups to a similar extent. Conclusion: SIT in hypoxia combined with nitrate supplementation increases the proportion of type IIa fibers in muscle, which may be associated with enhanced performance in short maximal exercise. Compared with normoxic training, hypoxic SIT does not alter βhm or endurance and sprinting exercise performance.
  • Source 2: Popeye was right: Could nitrate-rich spinach enhance strength & fitness
  • Link: http://www.nutraingredients.com/Ingredients/Botanicals-Herbals/Popeye-was-right-Could-nitrate-rich-spinach-enhance-strength-fitness