RCP is an abbreviation with several common meanings depending on context. The three you’re most likely searching for are the Royal College of Physicians (a centuries-old medical institution), the respiratory compensation point (a key threshold in exercise physiology), or the Root Cause Protocol (a mineral-focused wellness approach). Here’s what each one means and why it matters.
Royal College of Physicians
The Royal College of Physicians (RCP) is the oldest medical college in England, founded in 1518 under a Royal Charter from King Henry VIII. It represents more than 40,000 physicians worldwide and serves as the leading professional body for doctors in the UK and internationally. If you’ve seen “RCP” referenced in medical guidelines, hospital policies, or public health reports, this is almost certainly the organization being cited.
The RCP’s core work falls into three areas: education, advocacy, and research. It sets standards for how diseases are diagnosed, influences how healthcare systems are designed, and promotes public health initiatives. It operates as an independent, clinically led organization, meaning its recommendations come from practicing physicians rather than government bodies or commercial interests. Many of the clinical guidelines used in British hospitals originate from RCP working groups, and its reports frequently shape health policy across the UK and beyond.
Respiratory Compensation Point in Exercise
In exercise science and sports medicine, RCP stands for the respiratory compensation point. It marks the intensity during exercise at which your breathing rate spikes sharply because your body can no longer buffer the acid building up in your muscles. Below this point, your breathing increases in a fairly steady, linear way as you work harder. Above it, your body essentially switches into overdrive, hyperventilating to blow off carbon dioxide and counteract the rising acidity in your blood.
The RCP is sometimes called the second ventilatory threshold (VT2), and while researchers debate the finer technical distinctions between these terms, they generally reflect the same physiological transition point. In testing, both occur at roughly 70% of peak power output. In terms of oxygen consumption, the RCP typically falls at about 85 to 88% of your VO2 max. Runners tend to hit it slightly higher (around 87 to 88%) than cyclists (around 85 to 86%).
Why It Matters for Training
For athletes and coaches, the RCP is a practical performance marker. It represents the highest workload you can sustain before that rapid, uncontrollable heavy breathing kicks in. Training at or just below this threshold improves your body’s ability to tolerate and clear lactic acid, which translates to holding a faster pace for longer in races. Many structured training plans use the RCP to set intensity zones for interval work and tempo sessions.
Clinical Use in Heart Patients
The RCP also has diagnostic value. During cardiopulmonary exercise testing, clinicians look at the relationship between breathing rate and carbon dioxide output. In cardiac patients, whether someone reaches the respiratory compensation point at all turns out to be meaningful. A study of 152 heart patients found that those who reached the RCP during testing had significantly better cardiopulmonary function: their peak oxygen uptake averaged 20.2 ml/min/kg compared to just 13.6 ml/min/kg in those who never reached it. They also had lower levels of BNP, a protein that rises with heart failure severity. In short, reaching the RCP during an exercise test is a sign that the heart and lungs are functioning relatively well, while failing to reach it can signal more advanced disease.
The Root Cause Protocol
The Root Cause Protocol is a wellness framework developed by Morley Robbins that focuses on rebalancing three minerals: magnesium, copper, and iron. Its central claim is that many chronic health problems stem from iron building up in tissues where it doesn’t belong, combined with insufficient bioavailable copper. Rather than treating individual symptoms or conditions, the protocol aims to restore mineral balance across the whole body.
The biological idea behind it centers on a protein called ceruloplasmin, which the body uses to move iron in and out of storage in the liver, spleen, and bone marrow. According to this framework, when ceruloplasmin levels are too low, iron gets stuck in tissues instead of circulating properly. That trapped, unbound iron then generates oxidative stress, essentially creating a kind of internal “rust” that disrupts energy production and metabolism. Robbins argues that this iron dysregulation sits at the root of many conditions that are typically treated with medications rather than mineral correction.
The protocol involves a combination of dietary changes, targeted supplements (primarily to boost magnesium and bioavailable copper), and the avoidance of certain common supplements like synthetic iron and vitamin D in isolation. It’s important to note that the Root Cause Protocol is not part of mainstream medicine. While the underlying biochemistry of ceruloplasmin and iron metabolism is well established in scientific literature, the protocol’s specific claims about treating a wide range of conditions through mineral rebalancing have not been validated in clinical trials. It has a dedicated following in alternative health communities, but most conventional physicians do not recommend it as a treatment framework.