Well Done Dave!
Dave started out as a complete beginner, thinking he had no hope of being to develop the strength to do chin-ups, let alone with a 30 second negative.
Using an ultra-slow negative on the last rep taps into how our nervous system recruits our muscle fibres. Completing an extra slow lowering phase will give the body extra stimulation to get stronger quicker.
One of the ‘secrets’ to being able to do chin-ups.