STRENGTH & MUSCLE BUILDING

STRENGTH & MUSCLE BUILDING

UNDER CONSTRUCTION – SPRING-SUMMER – 2023

MUSCLE 

KINESIOLOGY

  • Kinesiology – Neuromechanical Matching .
    – The principle of neuromechanical matching tells us that muscles (and regions of muscles) are activated in an exercise in proportion to their leverage.
    – We can use the principle of neuromechanical matching by looking at charts showing how leverages of muscles alter with:
    [1] Strength Curve – Joint Angle – Range of Motion
    [2] Plane of Motion
    [3] Position of the Joint (for two-joint muscles only)
    [4] Position of the Neighbouring Joint
  • Kinesiology – Regional Hypertrophy .
    – While muscles grow after strength training, they do not always grow evenly across the whole muscle
    – The precise regions within a muscle where that growth occurs seems to differ, depending on the exercise that is used during training.
    – Such differences can apparently occur either because of differences between heads of a muscle or because of differences within regions of single muscles.

TRAINING FACTORS

1. Anatomy

Origins and Insertions: does the muscle cross a single joint or two joints, and which direction does the joint move when the muscle contracts

What it is:
– It describes the way in which a muscle divides into several internal regions.
– Some muscles do not divide very strongly into separate regions (ex: biceps brachii); other muscles clearly subdivide into multiple compartments (ex: latissimus dorsi)

Why it matters:
– It helps us see whether we are definitely going to need multiple exercises to train the muscle.
– These regions usually serve different purposes, particularly if the muscle is capable of multiple joint actions (although it can occur for other reasons too)
– Often one region contributes to a greater extent to one joint action (ex: the proximal rectus femoris contributes more to hip flexion and distal to knee extension)

3. Internal moment arm lengths

What it is:
– The internal moment arm lengths of a muscle determine its leverage on the joint, and therefore its contribution to a joint moment, relative to other agonist muscles
– When several muscles work at a joint, the one with greatest leverage at any given point in the exercise ROM will contribute most at that same point
– When a muscle has multiple regions, the region with the best leverage at any given point in the exercise ROM will contribute most at that same point
Why it matters:
– When targeting one muscle within a group (or one region of a muscle) we can see the peak force in an exercise joint ROM; Peak Force can be altered in two key ways.
(1) Select an exercise according to external moment arm lengths; ex: squat and hip thrust train GMax, but the point in hip joint ROM where peak force occurs is different
(2) Alter external resistance type; ex: squats with weight or with heavy elastic resistance train GMax but the point in hip joint ROM where peak force occurs is different

4. Working sarcomere lengths

What it is:
– Working sarcomere lengths describe the lengths of the sarcomeres inside the fibers of muscle over its joint angle ROM
– Some muscles (ex: quadriceps) contain sarcomeres that are already very stretched even when they are only partway through their full joint angle ROM
– Other muscles (ex: biceps) contain sarcomeres that are not stretched even when they reach their full joint angle ROM
– Thus, sarcomere length (and not muscle length) is the important factor
Why it matters:
– It allows us to see if the muscle can experience:
(1) Active insufficiency – Muscles will be trained poorly by exercises involving peak forces at very short muscle lengths
– When a sarcomere is shortened excessively during a joint action, it ceases to produce force effectively because its actin and myosin myofilaments no longer overlap sufficiently. This is called active insufficiency.
– Therefore, when a muscle contains sarcomeres that can reach very short lengths, it will respond poorly if it is trained with peak forces at very short muscle lengths (as when using partial ROM or elastic resistance)
– Conversely, if a muscle contains sarcomeres that cannot reach very short lengths, it will *not* respond poorly if it is trained with peak forces at short muscle lengths, even if it is a two-joint muscle such as the hamstrings!
(2) Stretch-mediated hypertrophy – Muscles will be trained more effectively by exercises involving peak forces at very long muscle lengths
– When a muscle contains sarcomeres that can reach long lengths, it will respond better if it is trained with peak forces at long muscle lengths than if it is trained with peak forces at short muscle lengths (as when using partial ROM).
– Yet, if a muscle contains sarcomeres that cannot reach long lengths, it will respond similarly to being trained with peak forces at long or short muscle lengths. In fact, full and partial ranges of motion will cause similar hypertrophy
– This is why full ROM often (but not always) cause more hypertrophy than partial ROM

5. Susceptibility to muscle damage

What it is:
– The susceptibility of a muscle to damage is simply how easily a muscle is damaged by a standard workout
– Some muscles experience a great deal of damage in response to a workout (like the biceps brachii), while other muscles experience little damage (like the quadriceps)
(1) Fiber type proportion
– More oxidative (slow twitch) muscle fibers are far less easily damaged than less oxidative (fast twitch) muscle fibers
(2) Voluntary activation
– Muscles that are easy to activate fully will be more easily damaged than muscles that are very difficult to activate
– When a muscle has a high voluntary activation capacity (such as the hamstrings), it will be more easily damaged compared to a muscle with a similar fast twitch fiber proportion but with a low voluntary activation capacity (such as the quadriceps).
(3) Working sarcomere lengths
– Muscles that contain sarcomeres that can be stretched substantially will be more easily damaged
Why it matters:
– The amount of muscle damage that a muscle experiences after a workout is the main determinant of the frequency we can use for training it.
– When a muscle is easily damaged, we will either need to train it with less workout volume than other muscles, or with a lower frequency.
– In addition, it affects the cost-benefit calculation of using:
(1) exercises that involve peak forces at long muscle lengths, since these cause more muscle damage than exercises that involve peak forces at short muscle lengths
(2) single-joint and single-limb exercises, since these cause more muscle damage than multi-joint and two-limb exercises
(3) types of training that enhance muscle damage, such as short rest periods, advanced techniques (such as drop sets and pre-exhaustion), and large ranges of motion

TRAINING FACTORS – UPPER BODY

TRAINING FACTORS – LOWER BODY

TRAINING FACTORS – NECK-SPINE-PELVIS-ABS

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