Effect of application of Transcutaneous Electrical Nerve Stimulation on acupuncture points (Acu-TENS) on lung function in people with asthma

INTERVENTION: This is a randomised crossover study. Participants will attend for 4 visits, weekly apart. In the first visit, participants characteristics will be measured and they will perform a Eucapnic voluntary hyperventilation (EVH) test. On visits 2 to 4, participants will receive one the following interventions, in a random order, before undergoing the EVH test: 1) Acu‐TENS and placebo ventolin 2) Placebo‐TENS and placebo ventolin 3) Placebo‐TENS and ventolin Intervention: Acu‐TENS refers to the application of Transcutaneous electrical nerve stimulation (TENS) onto acupoints for reducing breathlessness, i.e. EX‐B1, Dingchuan, located on the lower border of 7th Cervical Vertebrae. The intervention will last for 45 minutes. Ten minutes before the end of the Acu‐TENS session, participants will receive 2 puffs of placebo‐ventolin. Placebo TENS is similar to Acu‐TENS with the application of the TENS onto EX‐B1 except the machine was disconnected inside such that there is no electrical output despite the machine screen is still activated. Placebo TENS will be applied for 45 minutes. Ten minutes before the end of the intervention, participants will be asked to use 2 puffs of ventolin or placebo‐ventolin (depending on the group allocation). CONDITION: Asthma PRIMARY OUTCOME: Percentage change in Forced expirtory flow volume in one second (FEV1) SECONDARY OUTCOME: Nil INCLUSION CRITERIA: Patients diagnosed with asthma, with FEV1 % predicted >75%