As a general rule, the type of fitness required for some sports and physically demanding hobbies falls into one of two categories:

1. aerobic fitness (walkers, long distance runners, swimmers and cyclists etc)
2. anaerobic fitness (sprinters, strength athletes, powerlifters, bobsleigh etc)

However, most athletes require both aerobic and anaerobic fitness, and all athletes will benefit from varying degrees of both, as there is nearly always some degree of crossover.  It is obvious to see that athletes such as rugby players, Crossfitters, boxers, middle distance runners, cyclists, swimmers etc require good levels of aerobic and anaerobic fitness.

Yet although endurance runners mostly require fantastic aerobic ability they also benefit from a degree of anaerobic ability. Conversely sprinters clearly require fantastic anaerobic strength / power but also a good aerobic base.

In the process of training these two main energy systems athletes might encounter a phenomenon called the interference effect.  This is basically where one type of training can affect (interfere with) the ability to train the other system and therefore blunt any adaptations from the alternate type of training.

The body adaptation to exercise stimulus adheres to the SAID principle - Specific Adaptation to Imposed Demand, whereby the body basically becomes better (more efficient) at the things it is consistently asked to do.  So, it seems rather obvious that an athlete focusing solely on lifting heavier and heavier weights will become stronger and stronger but will almost certainly not improve their ability to run a marathon. Conversely you don’t see many, if any, endurance athletes entering strongman competitions.

But, and it is a big but, all athletes will benefit from some degree of crossover: endurance runners benefit from strength training to help their bodies withstand the impact forces of running for extended periods of time.  Equally, strength athletes will benefit from some aerobic training so that they can strength-train for greater periods of time.

The issue here then is how to best manage the interference effect in order to maximise athletic development. This falls into three main categories: micro (short), meso (medium) and macro (long) cycles.  The microcycle describes a singular training session, the mesocycle is a few sessions over one or a few weeks and macrocycles are months long.

MICROCYCLE: this can refer to exercises within one session or a split routine over the course of a day. If you want to train strength, power, muscular endurance and aerobic endurance in one session or within different times of the day, then doing so in the above order will provide greater stimulus for physiological adaptations to occur.

Conversely, if you were to go for a long run or do a high intensity circuit first and then try to lift heavy weights afterward or later in the same day, your neuro-muscular system will be compromised, your body will be fatigued, your lifting ability reduced and therefore any potential strength adaptations will be negated.

MESOCYCLE: this can describe training periods of more than once a week for up to about two months. Repeating a similar training routine each week for a couple of months before changing that routine, allows you to focus on comparisons of previous weeks and improvements and allows you to create great stimulus for change, depending on your goals.

If you are training multiple times over a couple of weeks it is recommended to do heavy lifting, power work and plyometrics at the start of this cycle, active recovery / mobility mid -cycle and endurance work later in the cycle, allowing a day or two to recover before repeating the process. A strength athlete will bias training towards strength, whereas an endurance athlete will train endurance with greater frequency. So a weekly plan might look something like this:

• Monday - strength training (deadlift, pull ups, RDL, bench press)
• Tuesday - tempo run (60 minutes @90% MHR)
• Wednesday - hill intervals (warm up jog - 5 x 30s on / 60s off - cool down)
• Thursday - rest day
• Friday - fun (20 minutes bodyweight HIIT circuit or plyometrics)
• Saturday - long steady run (3 hrs @ 70% MHR)
• Sunday - active recovery (walk, yoga, gentle swim etc)

MACROCYCLE: here we are talking about Strength and Conditioning periodisation plans, centred around competitions / seasons / championships etc. This could be over the course of a couple of months or up to four years in the case of Olympic athletes.

The basic principle here is working in blocks of weeks or months that might look like this: Strength Phase - Power Phase  - General Preparatory Phase - Sports Specific Phase - In Season Training - Rest Phase.

As a general rule with the interference effect, correct strength training will have little or no effect on endurance training and adaptations, however endurance training can impact strength training and adaptations greatly.

Play with it and have fun.