The word 'Bala' refers to the strength of the body. It also indicates ability of the body or part of the body, to protect oneself against various harmful factors. In Ayurveda, some of the body constituents have been called as Bala owing to their key role in protecting body against multiple stressors. Imbalance of these is supposed to play the key role in making body susceptible to harmful agents and vulnerable to diseases of body as well as mind. Thus, one can find that, term 'Bala' which literally means strength is also used interchangeably with Vyadhikshamatwa which refers to the immunity of the individual.
Ayurveda describes process of disease development in the unique way. Weakness of the body building tissues i.e. dhatus along-with vitiation of doshas is considered to be the primary step in development of any disease. Thus, Ayurveda lays great emphasis on maintaining high strength of all the Dhatus. Bala is the entity which represents this strength constituted by all 7 dhatus. This strength encompasses both aspects, physical as well as mental. Naturally, when this kind of strength (physical as well as mental) is present in body, it can fight against various diseases by its own. Appraising this role of Bala in protecting body from harmful factors, it is also correlated with immunity and immune system of the body. Ayurveda acharyas have advised to assess this Bala of the individual before planning treatment for anyone. While offering knowledge about measures to prevent and treat multiple diseases, Ayurveda acharyas have given great importance to maintenance of this Bala at each and every stage of clinical management as well as conducting surgical procedures.
The word Bala has been used invariably for strength of mind, body and its components. It also stands for immunity and immune system in normal state. From the clinical perspective, Bala has been correlated with 2 entities viz. normal Kapha dosha and Ojus present in the body.
Ojus as Bala
According to Acharya Sushruta, 'Bala' is the synonym of 'Ojus'. Ojus is the quintessence of all 7 dhatus. It is also known as bioenergy or body component that helps in sustaining life. It is formed at the end of dhatu level pachana (metabolism) and it is believed to be teja (quintessence or cream) of all these dhatus.
तत्र रसादीनां शुक्रान्तानां धातूनां यत् परं तेजस्तत् खल्वोजस्तदेव बलमित्युच्यते, स्वशास्त्रसिद्धान्तात् || (Sush. Samh. 15.19)
tatra rasādīnāṁ śukrāntānāṁ dhātūnāṁ yat paraṁ tejastat khalvojastadeva balamityucyate, svaśāstrasiddhāntāt ||
Kapha as Bala
Among 3 doshas controlling bodily functions, Kapha is the one that performs the function of strengthening and lubricating the body. Thus, 'Bala' also denotes the Kapha dosha in Prakrt awastha (normal state). Acharya Charaka has stated that role of Kapha dosha in balanced state or role of Ojus is same as Bala. Thus, Bala has also been defined as the kapha dosha which is in unaltered, non-vitiated or natural state.
प्राकृतस्तु बलं श्लेष्मा विकृतो मल उच्यते| स चैवौजः स्मृतः काये स च पाप्मोपदिश्यते||- (Char. Samh. 17.117)
prākr̥tastu balaṁ śleṣmā vikr̥to mala ucyate| sa caivaujaḥ smr̥taḥ kāye sa ca pāpmopadiśyate||
Role of Bala
Acharya Sushruta has clearly described various functions or advantages of having Bala.
तत्र बलेन स्थिरोपचितमांसता सर्वचेष्टास्वप्रतिघातः स्वरवर्णप्रसादो बाह्यानामाभ्यन्तराणां च करणानामात्मकार्यप्रतिपत्तिर्भवति ||२०|| (Sush. Samh. 15.20)
tatra balena sthiropacitamāṁsatā sarvaceṣṭāsvapratighātaḥ svaravarṇaprasādo bāhyānāmābhyantarāṇāṁ ca karaṇānāmātmakāryapratipattirbhavati ||20||
He states that, if an individual has enough strength then he can benefit in various ways as below,
- Nourishment and stability of Mamsa dhatu ( the muscular tissues of the body) can be obtained.
- An individual becomes capable of performing various tasks efficiently and uninhibitedly
- One achieves good complexion as well as clearness and pleasantness of voice
- Excellent Bala also facilitates clear, efficient working of all the organs either external like Indriyas [Jnyaanendriya (sense organs) or Karmendriya (organs with motor functions)] and internal like Manas (mind), Buddhi (Intellect) etc
Classification of Bala
The Bala of the individual could have various aspects. Some individuals possess strength naturally while some may lack this strength even after following rigorous diet, exercise and use of medicines. Similarly role of Kala is also considered significant by Ayurveda in maintaining this strength of the individuals. Considering all these factors, Ayurveda acharyas have classified the Bala of an individual in 3 components. Acharya Charaka has mentioned 3 types of Bala  as below,
- Sahaja (Natural, Present right from the birth)
- Kalaja (Present due to particular season and age) and
- Yuktikrita (Obtained by deliberate efforts to acquire strength like use of diet, exercise, medicines).
Ayurveda offers ways to improve Yuktikruta Bala of an individuals. Also, under topics like Rtucharya and Swasthavrtta, level of Kalaja Bala has been explained. The methods to preserve Bala which is lowered due to seasonal variations, have been mentioned. Multiple herbs, dietary components, activities and medicines that can enhance Bala of purusha have been described at places in classical Ayurveda treatises. At each and every point of describing any medical intervention, Ayurveda acharyas have given undisputed attention to bala of the patient and further management has been recommended on that basis. Such an approach in planning medicinal treatment while keeping an eye on strength of individual ensures safe and holistic healing with Ayurveda treatments. Various branches of Ayurveda like Rasayana (Tonic that nourishes all the tissues of the body) and Vajikarana (Invigorating and aphrodisiac medicine) primarily focus on enhancing this Yuktikrita bala. In this context, Bala is considered as effect of the food, medicine or activities which are having the action of nourishment.
Balya as karmas in Ayurveda
The pharmacodynamic activities of herbs have been described under Dravya karmas (actions of medicinal substances) in Ayurveda. One of these actions is named as Balya. Balya is defined as 'that which is beneficial and tend to increase Bala of an individual'. Balya herbs, medicinal substances, foods and activities improve the strength by nourishing all dhatus which form all organs and systems of the body.
Vaidyas make use of Balya medicines and advice Balya activities and diet during and after the treatment in order to regain the lost strength of shariram (body) after combating an illness. This helps to keep individual healthy, fit, devoid of harmful side effects caused by strong medicines and also helps to make one immune in order to prevent recurrence of similar diseases. Emergence of concepts of nutritional supplements in the contemporary science share similar ground however the approach of Ayurveda is more holistic and tailored to the needs of an individual.
Strength promoting drugs (Balya dravya)
Herbs like Bala (Sida cordifolia), Atibala (Abutilon indicum), Ashwagandha (Withania somnifera), Shatavari (Asparagus racemosus), Guduchi (Tinospora cordifolia), Payasya, Katuki, Ripened fruit of mango, Vidarikanda (Pueraria tuberose), Haritaki (Terminalia chebula), Amalaki (Emblica ofcinalis), Bibhitaki  are known to display Balya action when consumed in authentic way under the supervision of a learned Vaidya. Many of these herbs are well-known rejuvenator herbs and thus provide strength by nourishing all dhatus. However, these miraculous herbs may not show desired effects when used in an irrational way. One should take these at appropriate time, stage, in proper dosage followed by specific Anupana (Adjuvant) which are decided after thorough assessment of an individual by Vaidya.
Assessment of Bala
Since bala of the individual should be assessed before planning any Ayurveda treatment, one needs to know the method to assess this bala. Methods of examination of bala is mentioned in classical Ayurvedic texts and it is mostly based on anumana pramana ( inference). Vyayamashakti (The capacity of exercising) is considered to be the parameter for assessment of bala. Details on Vyayama, its benefits, the symptoms observed after completing exercise equivalent with level of bala have been described in classical treatises. Similarly a guideline to asses Manasika bala (strength of mind) can also be found in Ayurveda literature. It is said that Manasika bala is can be understood by knowing the level of Utsaha (Enthusiasm) in individual.
The normal state of bala constitutes the following sign in an individual
a. Sthira upachita māmsa : All the dhātus are equally produced and the resultant effect is growth of the body.
b. Sarvacheṣṭa: (Kāyika and mānasika cheṣṭa): Endeavor in physically and mentally.
c. Aprtighāta: Strong working capability with bhārvahanādi
d. Swara varṇa Prasāda: Clear vocal tone and normal complexion
e. bāhya karaṇa: That is specific function of Vak: vachan (speech); Pani: Adana (swap over); Pada: Gaman (movement); Payu: Visarga (excretion); Upastha: Nandana (pleasure).
f. Abhyantar karan: Srotra: Sabda(sound); Twaka: Sparsha(touch); Cakshu: Rupa(vision); Jibha: Rasa(taste); Nashika: Gandha(smell) etc. If all the above functions are normal, then we can say bala is in normal state.
Bala and immunity
Internally bala is expressed through vyadhi kshamatwa. Vyadhi kshamatwa indicates the strength by which a person fights against the disease. Inside that is the process by which vyadhi prativandhyakatwa is provided. Modern science has also mentioned about immunity. Immunity can be defined as the self preparedness against invasion by microbes which also includes defense against non microbial antigens and malignancy. Classically it is divided into two categories. a. The non- specific immunity or the innate immunity is not affected by prior contact with the invader and it is effective against all without recognizing the specific identities of the enemies i.e Vyadhibala virudhitwa. It is composed of many factors. Firstly the constitutional factor due to which some individuals are more prone to some specific infections but others are not. b. The specific immunity: There is separate mechanism for each and every enemy (antigens).The weapon for one invader will not act against the other hence called specific. This immunity develops properly only when the body is exposed to the specific antigen. i. e. prior contact is essential, but the provision is inborn, means sahaja. The specific immunity may be active or passive. Active immunity is developed within the body by the lymphocytes against antigens introduced in to the body i. e. vyadhi utpada prativandhakatwa. The passive immunity occurs due to transfer or introduction of antibodies from outside. It is a readymade immunity and can act immediately but it is short lasting.
मनोबलम् ॥ Effect of Trigunas on the strength of mind
In Ayurveda, the term Balam is used to indicate strength of a physical body or mind. The strength of mind is believed to be the that factor which decides the level of imbalances occurring in a persons mind on an encounter with undesirable, painful accident of any kind. It also indicates ability of the mind to protect oneself against various stressors. These imbalances later also reflect upon physical body ultimately affecting one's health, well-being and overall quality of a life. In this way strength of mind can also be compared with the tolerance level of mind and emotions a person. More the strangth or tolerance capacity, lesss prone the person is to stressful and unpleasant circumstances. Thus one can say that, the term Manobalam literally refers to psychological immunity of a person. It is believed that these trigunas play key role in development of psychological strenth and immunity in a person in a following manner.
सत्त्वे उत्तमं मनोबलं, रजसि मध्यमं मनोबलं, तमसि मनोदौर्बल्यमेवेति ॥ (Sush Samh 35.38) 
sattve uttamaṁ manobalaṁ, rajasi madhyamaṁ manobalaṁ, tamasi manodaurbalyameveti ॥ (Sush Samh 35.38)
Meaning: The strength of mind is best due to Sattva, moderate due to Rajas whereas the mind is weak due to presence or predominance of tamas.
Acharya Sushruta has clarified that, the strength of mind varies depending on the levels of trigunas in one's mind. The person the psychologically and emotionally strongest when there is predominance of sattva in mind and emotionally and psychologically vulnerable or weak when tamas is predominant in mind. Rajas level in manas makes one moderately strong while dealing stressful and unpleasant situations.
- Mahesh TS, Shreevidya M. A review on balya action mentioned in Ayurveda. J Ayurveda Integr Med. 2014;5(2):80–84. doi:10.4103/0975-9476.133796
- Sushrut Samhita (Sutrastanam Adhyaya 15 Sutra 19)
- Charaka Samhita (Sutrasthanam Adhyaya 17 Sutra 117)
- Sushrut Samhita (Sutrastanam Adhyaya 15 Sutra 20)
- Charaka Samhita (Sutrasthanam Adhyaya 11 Sutram 36)
- Nath et al. CLINICAL EXAMINATION OF BALA (STRENGTH). UJAHM 2015, 03 (04): Page 103-108
- Sushruta Samhita (Sutrasthanam Adhyayam 35 Sutram 38)